Stone to Ounce Converter

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.

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:

1. Emotional connection: Body weight is personal; changing units feels invasive
2. Convenient range: For adults, weight is 8-20 stones (easy to remember vs. 50-127 kg)
3. Medical exemption: Doctors use stones, so patients use stones
4. Social reinforcement: Everyone around you uses stones, so you do too

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!"