Kati (India) to Ounce Converter

The ounce (symbol: oz, from Italian onza) is a unit of mass equal to exactly 1/16 of an avoirdupois pound, which is 28.349523125 grams in the metric system.

Avoirdupois Ounce vs. Troy Ounce

When Americans say "ounce" in everyday life, they almost always mean the avoirdupois ounce (28.35 g). However, there's a second type of ounce:

Avoirdupois Ounce (Standard Ounce):

• 28.35 grams
• Used for: food, cooking, postal weight, groceries, body weight, general commerce
• 16 ounces = 1 avoirdupois pound

Troy Ounce:

• 31.10 grams (about 10% heavier)
• Used exclusively for: precious metals (gold, silver, platinum), gemstones, gunpowder
• 12 troy ounces = 1 troy pound
• Abbreviated: "oz t" or "ozt"

Critical distinction: When buying gold or silver, prices are quoted per troy ounce (31.1 g), not avoirdupois ounce (28.35 g). A troy ounce is about 2.75 grams heavier than a standard ounce.

Roman Origins: The Uncia

Latin Etymology: The word "ounce" comes from the Latin "uncia," meaning "one-twelfth" (related to "inch," from the same root).

Roman Measurement: In ancient Rome, the uncia was 1/12 of a Roman pound (libra), approximately 27 grams. The Romans used base-12 (duodecimal) systems for many measurements.

Symbol Origin: The abbreviation "oz" comes from the medieval Italian word onza (ounce), not from any English word starting with "o" and "z."

Medieval European Variation

Regional Chaos: Throughout medieval Europe, dozens of different "ounces" existed, varying by region, city, and trade guild. An ounce in Paris differed from an ounce in London, Venice, or Amsterdam.

Two Main English Systems:

Troy System (for precious goods):

• Used for gold, silver, jewels, and later gunpowder
• Troy ounce: 31.1 grams
• 12 troy ounces = 1 troy pound
• Named after Troyes, France, site of important medieval trade fairs

Avoirdupois System (for bulk goods):

• From French avoir de pois ("goods of weight")
• Used for wool, grain, cheese, meat—everyday bulk commodities
• Avoirdupois ounce: 28.35 grams
• 16 avoirdupois ounces = 1 avoirdupois pound
• Developed by medieval merchants for practical trade

English Standardization

1300s-1500s: Gradual Standardization: English monarchs attempted to standardize weights and measures, but variation persisted.

1588: Queen Elizabeth I: Confirmed the avoirdupois system for general trade, establishing 16 ounces per pound for commerce.

Troy System Preserved: The troy ounce remained the standard for precious metals, a tradition maintained to this day.

1959: International Agreement

Modern Definition: The 1959 international yard and pound agreement between the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa defined:

• 1 pound (avoirdupois) = exactly 453.59237 grams
• 1 ounce (avoirdupois) = exactly 1/16 pound = 28.349523125 grams

This eliminated minor variations between US and British measurements and anchored imperial units to the metric system.

Cooking and Baking

Recipe Measurements: American recipes commonly specify ingredient weights in ounces:

• Dry ingredients: flour, sugar, chocolate chips, nuts
• Solid fats: butter, shortening, cream cheese
• Proteins: chicken breasts (6 oz), ground beef (12 oz)

Kitchen Scales: Digital kitchen scales display weight in ounces (and grams), allowing precise measurement:

• Toggle between oz and g
• Tare function to zero out container weight
• Precision to 0.1 oz or 1 gram

Baker's Preference: Professional bakers prefer weight (ounces) over volume (cups) because:

• More accurate and consistent
• Eliminates measurement errors
• Works regardless of how ingredients settle or compact