Troy Ounce to Stone Converter
Convert troy ounces to stones with our free online weight converter.
Quick Answer
1 Troy Ounce = 0.004898 stones
Formula: Troy Ounce × conversion factor = Stone
Use the calculator below for instant, accurate conversions.
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All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.
Troy Ounce to Stone Calculator
How to Use the Troy Ounce to Stone Calculator:
- Enter the value you want to convert in the 'From' field (Troy Ounce).
- The converted value in Stone will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Weight category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Troy Ounce to Stone: Step-by-Step Guide
Converting Troy Ounce to Stone involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Troy Ounce = 0.00489796 stonesExample Calculation:
Convert 5 troy ounces: 5 × 0.00489796 = 0.0244898 stones
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other weight units?
View all Weight conversions →What is a Troy Ounce and a Stone?
1 troy ounce = 31.1034768 grams (g) = 480 grains
The troy ounce (abbreviated "oz t", "ozt", or "t oz") is a unit of mass in the troy weight system, used exclusively for precious metals and gemstones. It differs significantly from the avoirdupois ounce used in everyday measurements.
Troy vs. Avoirdupois: Critical Distinction
| Unit | Grams | Use Cases | |----------|-----------|---------------| | Troy ounce | 31.1034768 g | Precious metals (gold, silver, platinum), gemstones, pharmaceuticals (historic) | | Avoirdupois ounce | 28.349523125 g | Food, body weight, general commerce | | Difference | +2.754 g (9.7% heavier) | Troy ounce is HEAVIER |
Critical for buyers: If someone sells you "1 ounce of gold" using avoirdupois ounces instead of troy ounces, you're getting 9.7% less metal than you paid for!
The Troy Weight System
Unlike the avoirdupois system (16 ounces = 1 pound), the troy system uses different ratios:
- 24 grains = 1 pennyweight (dwt)
- 20 pennyweights = 1 troy ounce (oz t)
- 12 troy ounces = 1 troy pound (lb t)
Paradox: The troy ounce is heavier than the avoirdupois ounce, BUT the troy pound (373.24 g) is lighter than the avoirdupois pound (453.59 g) because it contains only 12 ounces instead of 16!
Why Troy Ounces Persist
Despite global metrication, troy ounces remain dominant in precious metals for these reasons:
- Market convention: Centuries of gold/silver trading established price benchmarks in troy ounces
- Legal tender: U.S. Mint, Royal Canadian Mint, and others mint official coins in troy ounce denominations
- Futures contracts: COMEX gold contracts specify 100 troy ounces per contract
- LBMA standards: London Bullion Market Association requires troy ounce quotations
- Central banks: Gold reserves reported in troy ounces (e.g., Fort Knox holds 147.3 million oz t)
1 stone = 14 avoirdupois pounds (lb) = 6.35029318 kilograms (kg) EXACT
The stone (symbol: st) is a unit of mass in the Imperial system, legally defined in terms of pounds, which are themselves defined in terms of kilograms. The exact conversion is:
1 pound = 0.45359237 kilograms (international definition, 1959)
1 stone = 14 × 0.45359237 kg = 6.35029318 kg
Stone and Pounds Notation
The stone is almost never used alone for body weight. Instead, it's combined with additional pounds:
Format: "X stone Y pounds" or "X st Y lb"
Examples:
- 10 st 0 lb = 10 stone exactly = 140 lb = 63.5 kg
- 10 st 7 lb = 10 stone + 7 pounds = 147 lb = 66.7 kg
- 12 st 3 lb = 12 stone + 3 pounds = 171 lb = 77.6 kg
Why this format? It provides precision without unwieldy decimal places. Saying "10.5 stone" is rare—people say "10 stone 7" instead (10 stone + 7 pounds = 10.5 stone).
Stone vs. Kilogram vs. Pound
Three systems for measuring body weight:
| System | Unit | Used In | Precision | |-----------|----------|-------------|---------------| | Imperial (UK) | Stone + Pounds | UK, Ireland | "11 st 7 lb" (161 lb) | | Imperial (US) | Pounds only | United States, Canada | "161 lb" | | Metric | Kilograms | Most of the world | "73 kg" |
Cultural difference:
- Americans say "I weigh 161 pounds"
- British say "I weigh 11 stone 7" (rarely "161 pounds")
- Europeans say "I weigh 73 kilograms"
Why 14 Pounds?
The number 14 has no scientific basis—it's purely historical. Medieval England used base-12 counting (duodecimal) for some systems:
- 12 inches = 1 foot
- 12 pence = 1 shilling (pre-1971)
- But 14 pounds = 1 stone (not 12!)
Theory: The 14-pound wool stone emerged from trade practices. A "sack of wool" weighed 364 pounds = 26 stones (26 × 14 = 364), a convenient round number for taxation and commerce.
Note: The Troy Ounce is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Stone belongs to the imperial/US customary system.
History of the Troy Ounce and Stone
Ancient and Medieval Origins (Pre-1500)
The word "ounce" derives from the Latin "uncia" (one-twelfth), reflecting the Roman system where 1 uncia = 1/12 of a libra (pound). The troy system's specific origins trace to Troyes, France, a major European trade city.
12th-15th centuries - Champagne Fairs: Troyes hosted international trade fairs where merchants from Italy, Flanders, England, and German states exchanged goods. Precious metals, spices, and textiles required standardized weights. The "Troyes weight" system emerged as a trusted standard for valuable commodities, particularly gold, silver, and gemstones.
Why "troy" not "avoirdupois"? Two parallel weight systems developed:
- Troy weights: For precious metals, spices, medicines (high-value, small quantities)
- Avoirdupois weights: For bulk goods like wool, grain, iron (from French "avoir de pois" = goods of weight)
English Standardization (1500-1800)
1527 - King Henry VIII standardization: Henry VIII officially defined troy weights for the English realm, establishing:
- 1 troy pound = 5,760 grains
- 1 troy ounce = 480 grains
- 1 grain = 64.79891 milligrams (based on barley grain weight)
1758 - British assay offices: The Goldsmiths' Company and assay offices in London, Birmingham, Sheffield, and Edinburgh used troy ounces exclusively for hallmarking gold and silver items. This reinforced troy ounces as the legal standard for precious metals in British commerce.
The Tower Pound obsolescence: England previously used the "Tower pound" for minting coins (5,400 grains), but troy weights (5,760 grains per pound) eventually replaced it in 1527, creating unified standards for bullion and coinage.
American Adoption (1776-1900)
1776-1792 - Early United States: American colonies inherited British troy standards. The early U.S. used Spanish silver dollars and British gold sovereigns, all measured in troy ounces.
1828 - U.S. Coinage Act: Congress officially adopted troy weights for all U.S. coinage. The Act specified:
- Gold dollar = 25.8 grains (1.672 g) of 90% gold
- Silver dollar = 412.5 grains (26.73 g) of 90% silver
- All coins measured in troy grains
1849-1855 - California Gold Rush: The discovery of gold at Sutter's Mill created massive demand for standardized weights. Assay offices in San Francisco weighed gold dust and nuggets in troy ounces, establishing the unit in the American West.
1873 - Coinage Act ("Crime of 1873"): This act demonetized silver, ending bimetallism. However, troy ounces remained the standard for measuring both gold and silver bullion.
Global Standardization (1900-Present)
1900-1971 - The Gold Standard era: Most nations tied currencies to gold reserves, measured in troy ounces:
- 1900: Gold Standard Act (U.S. fixed $20.67 per troy ounce)
- 1933: FDR revalued gold to $35 per troy ounce
- 1944: Bretton Woods Agreement ($35/oz t peg)
- 1971: Nixon ended gold convertibility, but troy ounce pricing persisted
1919 - London Bullion Market Association (LBMA): Founded to standardize London gold market practices. LBMA established:
- Good Delivery bars: 350-430 troy ounces (typically 400 oz t)
- Minimum purity: 995 parts per 1,000 (99.5% pure gold)
- Troy ounce quotations for spot prices
1974 - COMEX gold futures: The Commodity Exchange (COMEX) in New York launched gold futures contracts:
- Contract size: 100 troy ounces
- Delivery specifications: 1 kg bars (32.1507 oz t) or 100 oz bars
- Global price discovery mechanism
1975 - Gold ownership legalization: U.S. citizens regained the right to own gold bullion (banned since 1933). Investment coins like the Krugerrand (1 oz t), Canadian Maple Leaf (1 oz t), and American Gold Eagle (1 oz t) popularized troy ounce denominations for retail investors.
2000s-Present - Digital age: Despite metrication, troy ounces dominate:
- ETFs: SPDR Gold Shares (GLD) holds 900+ tons (28.9M oz t)
- Central banks: Reserve holdings reported in troy ounces (U.S. 261.5M oz t, Germany 108.9M oz t)
- Spot prices: Bloomberg, Reuters, Kitco quote gold/silver per troy ounce
- Refineries: Swiss refiners (PAMP, Valcambi) produce bars in troy ounce sizes
Cultural Significance
The troy ounce represents continuity in global finance—a medieval trade standard that survived the industrial revolution, world wars, and digital transformation. While most historical units vanished with metrication, the troy ounce persists because precious metals markets value tradition, legal precedent, and universal standardization over decimal convenience.
Ancient and Medieval Origins (Pre-1300)
The concept of standardized stones: Before precise metallic weights, communities used stones as trade counterweights. A merchant would keep a reference stone in the marketplace, verified by local authorities, against which goods were weighed.
Advantages:
- Durability: Stones don't corrode or wear like metal
- Availability: Every village had stones
- Tamper-resistance: Hard to secretly shave weight off a stone
Problem: Every region had different stones! The "stone of wool" in Yorkshire differed from the "stone of wool" in Kent.
Medieval Standardization Attempts (1300-1824)
Edward III's wool stone (1340): King Edward III standardized the wool stone at 14 pounds as part of regulating the lucrative wool trade (England's economic backbone in the Middle Ages). The "sack of wool" was defined as 364 pounds = 26 stones.
Commodity-specific stones: Different goods had different stone weights:
| Commodity | Stone Weight | Reasoning | |--------------|-----------------|---------------| | Wool | 14 lb (6.35 kg) | Trade standard | | Meat | 8 lb (3.63 kg) | Butcher's stone | | Glass | 5 lb (2.27 kg) | Fragile goods | | Cheese | 16 lb (7.26 kg) | Agricultural products | | Iron | Variable (8-15 lb) | Regional differences |
Why different weights? Practical reasons:
- Heavy commodities (iron, lead): Smaller stone weight made counting easier
- Light, valuable goods (wool, spices): Larger stone weight reduced fractions
- Tradition: Each guild jealously guarded its customary weights
The Weights and Measures Act 1824
The problem: By 1800, Britain had dozens of incompatible stone definitions, creating chaos in trade and taxation.
The solution: The 1824 Act standardized British weights and measures:
- 14 pounds = 1 stone (for general use, not tied to specific commodities)
- Stone officially defined in relation to the pound
- Commodity-specific stones discouraged (but not banned)
Imperial standardization: The Act also defined:
- 1 pound = 7,000 grains
- 16 ounces = 1 pound
- 14 pounds = 1 stone
- 8 stone = 1 hundredweight (112 pounds)
- 20 hundredweight = 1 ton (2,240 pounds)
Body weight adoption: The Victorian era (1837-1901) saw the stone become the standard for human weighing. Bathroom scales, medical records, and public health data used stones and pounds.
Metrication and Persistence (1965-Present)
The Weights and Measures Act 1965: The UK officially adopted the metric system, making kilograms the legal unit for trade. However, the Act exempted personal weighing—bathroom scales could continue showing stones.
Why the exemption?
- Cultural resistance: Brits refused to abandon stones for body weight
- Economic lobbying: Scale manufacturers didn't want to retool
- Medical inertia: NHS records already used stones; conversion would be costly
The result: 60+ years later, the stone persists:
- Bathroom scales: Default to stones in the UK (even modern digital ones)
- NHS medical records: Still record patient weight in stones/pounds
- Weight loss programs: Slimming World, Weight Watchers UK use stones
- Media: British newspapers report celebrity weight in stones
- Sports: Boxing, horse racing, rowing use stones for weight classes
Ireland's experience: Ireland officially adopted metric units in 2005, but the stone remains common for body weight, especially among older generations.
Generational divide:
- Older Brits (60+): Think exclusively in stones
- Middle-aged (30-60): Bilingual (stones and kilograms)
- Younger (<30): Increasingly use kilograms, but still understand stones
Cultural Tenacity
The stone is the most persistent Imperial unit in British daily life, outlasting:
- Fahrenheit: Replaced by Celsius (weather, ovens)
- Inches/feet for height: Partially replaced by metres (though feet still common)
- Pints: Milk sold in litres (though beer still sold in pints!)
- Miles: Road signs still use miles (the UK never fully switched)
Why the stone survives:
- Emotional connection: Body weight is personal; changing units feels invasive
- Convenient range: For adults, weight is 8-20 stones (easy to remember vs. 50-127 kg)
- Medical exemption: Doctors use stones, so patients use stones
- Social reinforcement: Everyone around you uses stones, so you do too
Common Uses and Applications: troy ounces vs stones
Explore the typical applications for both Troy Ounce (imperial/US) and Stone (imperial/US) to understand their common contexts.
Common Uses for troy ounces
1. Precious Metals Trading
The troy ounce is the universal standard for global bullion markets:
Spot price quotations:
- Gold: $1,800-2,100 per troy ounce (fluctuates with markets)
- Silver: $20-30 per oz t
- Platinum: $900-1,200 per oz t
- Palladium: $1,000-1,600 per oz t
- Rhodium: $3,000-15,000 per oz t (highest volatility)
Major markets:
- London Bullion Market (LBMA): Sets gold/silver fix twice daily in troy ounces
- COMEX (New York): Futures contracts (100 oz t gold, 5,000 oz t silver)
- Shanghai Gold Exchange: Trades gold in grams but converts to oz t for international quotes
- Dubai Gold Souk: Retail sales in grams, wholesale in troy ounces
Why troy ounces persist: Centuries of price history, legal contracts, and central bank reserves create network effects—changing to grams would require recalibrating trillions in financial instruments.
2. Investment Coins & Bars
Government minted coins (1 oz troy):
- American Gold Eagle: Most popular U.S. bullion coin, 22K gold
- Canadian Maple Leaf: 24K gold (.9999 fine), iconic design
- South African Krugerrand: First modern bullion coin (1967)
- Austrian Philharmonic: European alternative, euro-denominated
- Chinese Gold Panda: Annual design changes, collector value
Fractional coins:
- 1/2 oz, 1/4 oz, 1/10 oz troy ounce denominations
- Higher premiums per ounce (manufacturing costs)
- Easier to liquidate small amounts
Private mint bars:
- 1 oz, 10 oz, 100 oz troy ounce sizes (silver)
- 1 oz, 10 oz, 1 kg gold bars
- Lower premiums than coins (no numismatic value)
- Stackability for storage
3. Jewelry Manufacturing
Jewelers purchase gold in troy ounces but often work in grams or pennyweights (dwt):
Pricing structure:
- Spot price: Current troy ounce price (e.g., $2,000/oz)
- Karat adjustment: 14K = 58.3%, 18K = 75%, 22K = 91.67%
- Fabrication cost: Labor, design, gemstones
- Retail markup: 2-3× material cost
Example calculation (14K ring):
- Weight: 5 grams = 0.16075 oz t
- Pure gold: 0.16075 × 0.583 = 0.0938 oz t
- Gold value: 0.0938 × $2,000 = $187.60
- Retail price: $500-800 (includes labor, overhead, profit)
Scrap gold recycling: Jewelers sell scrap in troy ounces to refineries, receiving 90-95% of spot price (refining losses, processing fees).
4. Pharmaceutical & Apothecary (Historic)
Before metrication, pharmacists used troy weights for compounding:
Apothecaries' system:
- 20 grains = 1 scruple
- 3 scruples = 1 dram
- 8 drams = 1 troy ounce
Modern legacy:
- Grain measurements persist (aspirin: 5 grains = 325 mg)
- Troy ounces phased out in medicine by 1970s
- Replaced by milligrams and grams for precision
5. Mining & Geology
Gold production and ore grades measured in troy ounces:
Reserve reporting:
- Gold deposits: "10 million oz t at 2 g/t grade" (metric tons ore, troy ounces gold)
- Production rates: "500,000 oz t per year" (annual mine output)
Ore grades:
- High-grade: 10-20 g/t (0.32-0.64 oz t per metric ton ore)
- Low-grade: 1-5 g/t (0.032-0.16 oz t/t)
- Ultra-low-grade: 0.5 g/t (economical with modern extraction)
Example (Nevada Gold Mine):
- Reserves: 50 million metric tons
- Grade: 2 g/t (0.064 oz t/t)
- Contained gold: 3.2 million troy ounces
- Mine life: 15 years (213,000 oz t/year production)
6. Central Banking & Reserves
Countries hold gold reserves measured in troy ounces:
Reserve valuation: Most central banks value gold at historic cost ($42.22/oz t, a 1973 price), not market rates. However, market value uses current spot prices:
- U.S. reserves: 261.5M oz t × $2,000 = $523 billion market value
- Official books: 261.5M oz t × $42.22 = $11 billion (!)
Reserve diversification:
- Gold as % of reserves: U.S. (70%), Germany (67%), Italy (64%)
- Rationale: Inflation hedge, currency crisis protection, geopolitical insurance
7. Collectibles & Numismatics
Coin collectors distinguish between bullion value (troy ounces) and numismatic value (rarity, condition):
Example: 1933 Double Eagle
- Gold content: 0.9675 oz t (~$1,935 melt value)
- Auction price: $18.9 million (2021 Sotheby's)
- Numismatic premium: 9,700× bullion value!
Modern bullion vs. collectible:
- Bullion: Trades at spot + 3-10% premium (1 oz Gold Eagle)
- Collectible: Rare dates, low mintages command 2-100× premiums
When to Use stones
1. Body Weight Measurement
The stone is the unit for body weight in the UK and Ireland.
Bathroom scales:
- Display: "11 st 7 lb" (digital) or analog dial with stone markings
- Dual units: Many scales toggle between st/lb and kg
- Default: Stones for UK-sold scales, even from international brands
Weighing yourself:
- British: "I'm 12 stone 3"
- American: "I'm 171 pounds"
- European: "I'm 78 kilograms"
Weight goals:
- "I want to lose a stone" = 14-pound goal
- "I'm aiming for 10 stone" = target weight
- "I've gained half a stone" = 7-pound increase
2. Medical and Healthcare
NHS patient records: British hospitals and GPs record weight in stones/pounds (with kg conversion).
Medical forms:
- Pre-op questionnaires: "Weight: __ st __ lb"
- Prescription dosing: Sometimes based on weight (converted to kg for calculations)
- Anesthesia planning: Weight in stones converted to kg for drug dosages
Maternity care:
- Booking appointment: "What was your pre-pregnancy weight?" (stones)
- Pregnancy weight tracking: "You've gained 2 stone, which is healthy"
- Post-natal: "Most women lose 1-2 stone in the first weeks"
Mental health context: Eating disorder treatment tracks weight changes in stones (e.g., anorexia recovery: "gained 1 stone to 7 stone 10").
3. Weight Loss and Fitness
Slimming clubs:
- Slimming World, Weight Watchers UK: Weigh-ins in stones
- Awards: "Half-stone hero," "Stone club," "3-stone milestone"
- Targets: "Lose 10% of body weight" (e.g., 1.5 stone from 15 stone start)
Fitness apps (UK versions):
- MyFitnessPal UK: Input weight in stones
- Fitbit/Garmin: UK users set goals in stones
- Weight tracking graphs: Y-axis shows stones, not kg
Personal trainers: British trainers discuss client progress in stones: "You've dropped from 14 stone to 12 stone 8—fantastic!"
4. Sports Weight Classes
Boxing: British boxing traditionally used stones for weight classes (now officially kilograms, but stones still common in commentary).
Horse racing:
- Jockey weights: Includes jockey + saddle + lead weights to meet required "riding weight"
- Handicapping: Horses carry different weights (in stones) to equalize competition
- Penalties: "Carrying 9 stone 7" vs. "Carrying 10 stone" affects race outcomes
Rowing: Lightweight rowers must weigh under certain stone limits (now metric, but historically stones).
5. Everyday Conversation
The stone pervades British informal speech:
Common phrases:
- "I'm 11 stone, give or take" = approximate weight
- "She must be 10 stone soaking wet" = very light
- "He's put on a stone since Christmas" = seasonal weight gain
- "I haven't been 9 stone since I was 15!" = nostalgic reference
Social etiquette:
- It's impolite to ask someone's weight directly, but acceptable to discuss your own
- Women might say "I'm trying to get back to 9 stone" (goal weight)
6. Media and Entertainment
British TV shows:
- Reality TV: "Love Island" contestants' weights discussed in tabloids (stones)
- Medical shows: "Embarrassing Bodies" references patient weight in stones
- Game shows: "The Biggest Loser UK" tracked loss in stones
Newspapers and magazines:
- Celebrity weight speculation: "Has she lost 2 stone?"
- Health articles: "How to lose half a stone by summer"
- Success stories: "I lost 8 stone and transformed my life!"
7. Historical and Cultural References
Literature: Victorian novels reference weight in stones:
- Dickens, Austen rarely mention specific weights (impolite)
- 20th-century literature: "She was a strapping girl of 12 stone"
British humor: Comedians joke about weight in stones:
- "I'm not overweight, I'm just undertall for my 14 stone!"
Generational markers:
- Older Brits: "When I got married, I was 8 stone"
- Modern comparison: "That's only 112 pounds—too thin by today's standards!"
Additional Unit Information
About Troy Ounce (oz t)
1. Is a troy ounce the same as a regular ounce?
No. The troy ounce (31.1035 g) is about 9.7% heavier than the avoirdupois ounce (28.3495 g) used for food and general items.
Visual comparison:
- 1 troy ounce gold = Size of a large grape (but very dense)
- 1 avoirdupois ounce flour = Same volume but less mass
When it matters: Precious metals (gold, silver, platinum) always use troy ounces. If someone offers you "1 ounce of gold" at a suspiciously low price, verify it's troy ounces—not avoirdupois!
2. How many grams are in a troy ounce?
Exactly 31.1034768 grams.
This precise definition comes from the 1959 international agreement on units. It's the same globally—LBMA (London), COMEX (New York), and Shanghai Gold Exchange all use this exact conversion.
For practical purposes:
- 1 troy oz ≈ 31.1 grams (rounded)
- 10 troy oz ≈ 311 grams
- 32.15 troy oz = 1 kilogram (exactly 1,000 g)
3. How many troy ounces are in a troy pound?
12 troy ounces = 1 troy pound (373.24 grams).
This differs from the avoirdupois system where 16 ounces = 1 pound. The troy system uses base-12 (duodecimal), a remnant of Roman and medieval counting systems.
Paradox explained:
- Troy ounce (31.10 g) > Avoirdupois ounce (28.35 g)
- BUT Troy pound (373.24 g) < Avoirdupois pound (453.59 g)
Why: 12 × 31.10 = 373.24, while 16 × 28.35 = 453.59.
4. Why do precious metals use troy ounces instead of grams?
Historical inertia and market convention.
Reasons troy ounces persist:
-
Centuries of price data: Gold has been priced per troy ounce since the 1700s. Changing would break historical charts and analysis.
-
Legal tender and contracts: U.S. Mint, Canadian Mint, and others legally define coins in troy ounces. Futures contracts, options, and derivatives are denominated in oz t.
-
Central bank reserves: Fort Knox holds "147.3 million troy ounces," not "4,582.7 metric tons"—the legal records use troy ounces.
-
Network effects: If London uses oz t, New York must too. Shanghai converts grams to oz t for international quotes.
-
Cultural identity: "An ounce of gold" evokes tangibility. "31.1 grams of gold" lacks the same resonance.
Metrication attempts failed: France and other metric-first countries tried quoting gold in grams, but international traders kept converting back to oz t for comparison.
5. How much is 1 troy ounce of gold worth?
It fluctuates constantly. As of 2024, gold trades between $1,800 - $2,100 per troy ounce, depending on economic conditions.
Price drivers:
- Inflation fears: Gold rises when currency value erodes
- Interest rates: Low rates → gold attractive (no yield anyway)
- Geopolitical crises: Wars, sanctions boost safe-haven demand
- Central bank buying: China, Russia, Turkey accumulating reserves
- Jewelry demand: India, China seasonal festivals
Historical context:
- 1900: $20.67/oz (Gold Standard Act)
- 1971: $35/oz (Nixon Shock, end of Bretton Woods)
- 1980: $850/oz (Hunt Brothers silver crisis, inflation)
- 2011: $1,900/oz (Financial crisis aftermath)
- 2020: $2,067/oz (COVID-19 pandemic peak)
Real-time prices: Check Bloomberg, Reuters, Kitco, or bullion dealer sites.
6. What's the difference between "carat" and "karat"?
Completely different units—one measures weight, the other purity:
CARAT (ct) = Gemstone weight
- 1 carat = 200 milligrams = 0.00643 troy ounces
- Measures diamonds, rubies, sapphires, emeralds
- "5-carat diamond" = 1 gram weight
KARAT (K or kt) = Gold purity
- 24K = 100% pure gold
- 18K = 75% gold (18/24)
- 14K = 58.3% gold (14/24)
- Measures alloy composition, not weight
Example: "18K gold ring weighing 0.2 troy ounces" means:
- Karat: 75% pure (18/24)
- Weight: 0.2 oz t = 6.22 g total
- Pure gold: 0.15 oz t = 4.67 g (6.22 × 0.75)
7. Can I buy fractional troy ounces?
Yes! Governments and private mints produce fractional coins:
Common sizes:
- 1/10 oz t (3.11 g) — Popular for small investors
- 1/4 oz t (7.78 g)
- 1/2 oz t (15.55 g)
- 1 oz t (31.10 g) — Most popular size
Trade-offs:
- Pros: Lower entry cost ($200 for 1/10 oz vs. $2,000 for 1 oz), easier to liquidate small amounts
- Cons: Higher premiums per ounce (1/10 oz costs ~15% premium vs. 3-5% for 1 oz)
Example:
- 1 oz Gold Eagle: $2,050 ($50 premium over $2,000 spot = 2.5%)
- 1/10 oz Gold Eagle: $240 ($40 premium over $200 spot = 20%!)
Why higher premiums? Minting costs don't scale linearly. Striking a 1/10 oz coin costs almost as much as a 1 oz coin, so the percentage premium is higher.
8. What is a "Good Delivery" gold bar?
The international standard for large-scale gold bullion, set by the London Bullion Market Association (LBMA).
Specifications:
- Weight: 350-430 troy ounces (typically 400 oz t = 12.4 kg)
- Purity: Minimum 995 parts per 1,000 (99.5% pure gold)
- Fineness stamp: Refinery mark, serial number, purity, year
- Refiners: LBMA-approved list (~70 refineries: PAMP, Valcambi, Rand, Johnson Matthey)
Why "Good Delivery"? Before standardization, banks had to assay every bar (costly, time-consuming). LBMA Good Delivery certification means bars are universally accepted without re-assaying.
Where they're used:
- Central bank reserves (Fort Knox, Bank of England vaults)
- Commercial bank vaults (HSBC, JPMorgan)
- ETF backing (SPDR Gold Shares stores Good Delivery bars)
Retail availability: Most investors never see Good Delivery bars—they're institutional. Retail investors buy 1 oz coins or small bars (1 oz, 10 oz, 100 oz).
9. How do I convert troy ounces to kilograms?
Formula:
1 troy ounce = 0.0311034768 kilograms
OR
1 kilogram = 32.1507466 troy ounces
Quick method: Divide troy ounces by 32.15 to get kilograms:
400 oz t ÷ 32.15 ≈ 12.44 kg
Precise method: Multiply troy ounces by 0.0311034768:
400 oz t × 0.0311034768 = 12.44139072 kg (EXACT)
Common conversions:
- 1 oz t = 0.0311 kg
- 10 oz t = 0.311 kg
- 100 oz t = 3.11 kg
- 1,000 oz t = 31.1 kg
- 32.15 oz t = 1 kg (exactly 1,000 g)
10. What's the smallest amount of gold I can buy?
Technically, you can buy any amount, but practical minimums exist:
Physical gold:
- Smallest coins: 1/10 oz t (~$200-250)
- Gold jewelry: Varies, but 14K chains start around $100-200 (contains ~0.05 oz t pure gold)
- Gold leaf: Decorative, negligible weight (~0.001 oz t per sheet)
Paper gold (no physical delivery):
- Gold ETFs (GLD, IAU): 1 share ≈ 0.1 oz t (~$200)
- Fractional platforms (OneGold, Vaulted): Buy as little as $1 worth (0.0005 oz t)
- Futures contracts: 100 oz t minimum (~$200,000—professional traders only)
Recommendation for beginners: Start with 1/4 oz or 1/2 oz coins (balance between affordability and premiums). Avoid tiny fractions (1/20 oz) due to extremely high premiums.
11. How do jewelers measure gold?
Three units, depending on context:
- Troy ounces (oz t): Buying gold from refineries, calculating melt value
- Pennyweights (dwt): Traditional unit (1 oz t = 20 dwt, 1 dwt = 1.555 g)
- Grams (g): Modern standard, easier math
Example (jeweler selling 14K scrap):
- Weighs scrap: 25.5 grams
- Converts to troy ounces: 25.5 ÷ 31.1 = 0.82 oz t
- Calculates pure gold: 0.82 × 0.583 (14K) = 0.478 oz t
- Refinery pays: 0.478 × $2,000 × 0.95 = $908 (95% of spot, 5% refining fee)
Pennyweight legacy: Older jewelers still use "dwt" for historic reasons. Most modern shops use grams for precision.
12. Why are central banks buying more gold?
Diversification away from the U.S. dollar and geopolitical hedging.
Key drivers:
- De-dollarization: Russia, China, Turkey reducing USD reserves after sanctions
- Inflation hedge: 2020-2024 inflation spikes drove safe-haven demand
- Currency debasement fears: Massive money printing (COVID stimulus) erodes fiat value
- Geopolitical tensions: Ukraine war, Taiwan tensions increase reserve gold holdings
Recent trends (2020-2024):
- China: Added 300+ tons (9.6M oz t) in 2023 alone
- Russia: Doubled reserves to 2,300 tons (74M oz t) before Ukraine war
- Poland: Increased from 103 to 228 tons (7.3M oz t)
- Singapore: Tripled reserves to 230 tons (7.4M oz t)
Why troy ounces matter: Central bank transactions are reported in troy ounces (IMF, World Gold Council standards), even though storage is often measured in metric tons.
About Stone (st)
1. How many pounds are in a stone?
Exactly 14 pounds.
This is a defined constant. There are no regional variations—1 stone always equals 14 pounds in any context.
Calculation examples:
- 5 stone = 5 × 14 = 70 pounds
- 12 stone = 12 × 14 = 168 pounds
- 0.5 stone = 0.5 × 14 = 7 pounds
2. Is the stone used outside the UK and Ireland?
Rarely. The stone is almost exclusive to the UK and Ireland.
Usage by country:
- UK: Dominant for body weight (even with official metrication)
- Ireland: Common, especially among older generations
- Canada, Australia, New Zealand: Not used (fully metric)
- United States: Not used (pounds only)
- Rest of world: Not used (metric)
Exception: British expats abroad sometimes use stones, and international weight loss forums may reference stones when discussing UK participants.
3. Why is it called a stone?
Historical practice: Actual stones were used as standardized weights in medieval markets.
How it worked:
- A community selected a reference stone of agreed weight
- The stone was kept in the marketplace (sometimes literally built into a wall)
- Merchants used the reference stone on balance scales to verify weights
- Different stones existed for different commodities (wool stone, meat stone, etc.)
Modern name: The unit name "stone" is a fossil of this practice, long after actual stones stopped being used.
4. How do you convert stone to kilograms?
Formula:
Kilograms = Stone × 6.35029318
Quick approximation:
Kilograms ≈ Stone × 6.35 (good to 3 decimal places)
Examples:
- 10 stone × 6.35 = 63.5 kg
- 12 stone × 6.35 = 76.2 kg
- 15 stone × 6.35 = 95.25 kg
Online tools: Most conversion sites and apps include stone ↔ kilogram calculators.
5. How do British people talk about their weight?
Typical format: "I'm X stone Y pounds" or "I'm X stone Y"
Examples:
- "I'm 11 stone 7" = 11 stone + 7 pounds = 161 lb = 73 kg
- "I'm just over 12 stone" = slightly more than 168 lb
- "I'm nearly 10 stone" = approaching 140 lb
Rarely said:
- "I'm 11.5 stone" (uncommon—people say "11 stone 7" instead)
- "I'm 161 pounds" (too American—Brits don't think in pounds alone)
- "I'm 73 kilograms" (used by younger generations, but less common)
Conversational weight: Discussing weight is somewhat taboo, so people often avoid specifics: "I need to lose a bit of weight" rather than "I need to drop from 13 to 11 stone."
6. Do British bathroom scales show kilograms?
Yes, most modern scales show both.
Typical features:
- Default: Stones and pounds (st/lb)
- Toggle button: Switch to kilograms
- Dual display: Some show both simultaneously
Older scales: Analog scales from before 2000 often show stones only.
Buying scales in the UK: Even international brands (Fitbit, Garmin) sell UK-specific versions that default to stones.
7. Will the UK ever stop using stones?
Unlikely in the near future.
Reasons for persistence:
- Cultural attachment: Body weight is personal; people resist change
- Legal exemption: Personal weighing scales exempt from trade regulations
- NHS inertia: Changing medical records costly
- Generational use: Older generations use stones exclusively
- No enforcement: No push to mandate kilograms for personal use
Trend: Younger Brits (under 30) increasingly use kilograms, especially those who travel or use fitness apps with international audiences. However, the stone will likely persist for decades among older populations.
Comparison: Similar to Fahrenheit in the US—officially discouraged but culturally entrenched.
8. What is a "half stone"?
Half stone = 7 pounds = 3.175 kg
Usage:
- Weight loss: "I've lost half a stone" = 7 lb loss
- Weight gain: "I've put on half a stone over Christmas" = 7 lb gain
- Milestones: "Half-stone club" in weight loss programs
Why significant? Half a stone is a noticeable weight change—enough to affect how clothes fit and how you feel, but achievable in 3-7 weeks of dieting (at 1-2 lb/week loss).
9. How do you write stone and pounds?
Common formats:
Formal:
- "11 stone 7 pounds"
- "11 st 7 lb"
Informal:
- "11 stone 7"
- "11st 7lb" (no spaces)
- "11-7" (very casual, context-dependent)
Avoid:
- "11.7 stone" (ambiguous—could mean 11 stone 7 lb or 11 stone 9.8 lb)
- "11/7 st" (confusing notation)
Medical records: NHS typically uses "st/lb" format: "Patient weight: 12 st 3 lb"
10. Why do Americans not use stone?
The United States never adopted the stone for body weight.
Historical reasons:
- Colonial divergence: By the time the stone standardized in Britain (1824), the US had already established pounds as the body weight unit
- Decimal preference: Americans favored simpler base-10 systems where possible
- No cultural push: No equivalent to UK's Victorian-era adoption of stones for weighing people
Result: Americans think in pounds only:
- "I weigh 180 pounds" (no stones)
- Weight loss: "I lost 30 pounds" (not "2 stone 2 pounds")
Canadian note: Canada officially metricated in the 1970s and uses kilograms, not stones or pounds (though older Canadians may still think in pounds).
11. Is stone a legal unit?
Yes, in the UK and Ireland, but with restrictions.
Legal status:
- Personal use: Fully legal (bathroom scales, self-weighing)
- Trade: Must use metric (kilograms) for selling goods by weight
- Medical: Allowed in patient records (NHS uses stones)
Weights and Measures Act: Kilograms are the legal unit for commerce, but stones remain legal for "non-trade" purposes (personal weighing, medical records).
Comparison: Similar to miles on UK road signs—officially metric, but exceptions preserve traditional units in specific contexts.
12. How much is a stone in other historical weight units?
Stone in troy and apothecary systems:
Troy weight (precious metals):
- 1 stone (avoirdupois) = 14 pounds (avoirdupois)
- 1 pound (avoirdupois) = 7,000 grains
- 1 stone = 98,000 grains (troy)
- 1 troy pound = 5,760 grains
- 1 stone ≈ 17.01 troy pounds
Apothecaries' weight (pharmacy):
- Same grain as troy and avoirdupois (64.79891 mg)
- 1 stone = 98,000 grains (apothecaries')
Why this matters: Historically, pharmacists used apothecaries' weights, so understanding stone conversions was important for dosing medicines based on body weight.
Conversion Table: Troy Ounce to Stone
| Troy Ounce (oz t) | Stone (st) |
|---|---|
| 0.5 | 0.002 |
| 1 | 0.005 |
| 1.5 | 0.007 |
| 2 | 0.01 |
| 5 | 0.025 |
| 10 | 0.049 |
| 25 | 0.122 |
| 50 | 0.245 |
| 100 | 0.49 |
| 250 | 1.225 |
| 500 | 2.449 |
| 1,000 | 4.898 |
People Also Ask
How do I convert Troy Ounce to Stone?
To convert Troy Ounce to Stone, enter the value in Troy Ounce in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our weight converter page to convert between other units in this category.
Learn more →What is the conversion factor from Troy Ounce to Stone?
The conversion factor depends on the specific relationship between Troy Ounce and Stone. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Stone back to Troy Ounce?
Yes! You can easily convert Stone back to Troy Ounce by using the swap button (⇌) in the calculator above, or by visiting our Stone to Troy Ounce converter page. You can also explore other weight conversions on our category page.
Learn more →What are common uses for Troy Ounce and Stone?
Troy Ounce and Stone are both standard units used in weight measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our weight converter for more conversion options.
For more weight conversion questions, visit our FAQ page or explore our conversion guides.
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⚖️ Metric vs Imperial
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All Weight Conversions
Other Weight Units and Conversions
Explore other weight units and their conversion options:
- Kilogram (kg) • Troy Ounce to Kilogram
- Gram (g) • Troy Ounce to Gram
- Milligram (mg) • Troy Ounce to Milligram
- Pound (lb) • Troy Ounce to Pound
- Ounce (oz) • Troy Ounce to Ounce
- Ton (metric) (t) • Troy Ounce to Ton (metric)
- Ton (US) (ton) • Troy Ounce to Ton (US)
- Ton (UK) (long ton) • Troy Ounce to Ton (UK)
- Microgram (µg) • Troy Ounce to Microgram
- Carat (ct) • Troy Ounce to Carat
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — US standards for weight and mass measurements
International Organization for Standardization — International standard for mechanics quantities
Last verified: December 3, 2025