An avoirdupois ounce is 1/16 pound.
Ounces to Grams Converter — oz to g
Convert Ounce (oz) to Gram (g) using the exact conversion factor (1 ounce = 28.34952313 gram). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Ounces to Grams converter
Converter
Mass/Weight Converter
Convert SI mass, imperial weight, jewelry, atomic, and astronomy mass units.
Context values
Some unit families need one extra value for a physically accurate result.
A gram is one thousandth of a kilogram.
Result = input x 0.02834952313 / 0.001.
Mass uses the kilogram as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Ounces to Grams
Weight conversions between Ounce and Gram come up constantly in everyday commerce, shipping, and cooking, since US packaging is usually labeled in pounds while most of the rest of the world uses kilograms. Ounce is typically associated with united States (cooking, postal, retail), while Gram is typically associated with standard small-mass unit worldwide.
Formula
grams = ounces × 28.349523125
This factor comes from each unit's defined relationship to the category's base unit: 1 ounce equals 0.028349523125 base units, and 1 gram equals 0.001 base units, so dividing one by the other gives the direct ounce-to-gram factor of 28.349523125.
Simple example
1 oz × 28.34952313 = 28.34952313 g
1 ounce = 28.34952313 grams.
Real-world example
50 oz × 28.34952313 = 1,417.476156 g
50 ounces = 1,417.476156 grams.
Conversion table
| Ounce (oz) | Gram (g) |
|---|---|
| 1 oz | 28.34952313 g |
| 5 oz | 141.7476156 g |
| 10 oz | 283.4952313 g |
| 25 oz | 708.7380781 g |
| 50 oz | 1,417.476156 g |
| 100 oz | 2,834.952313 g |
Reverse conversion: Gram to Ounce
28.34952313 g × 0.03527396195 = 1 oz
28.34952313 grams = 1 ounces.
ounces = grams × 0.0352739619496
For a page dedicated to this direction, see Gram to Ounce.
Ounce vs. Gram
| Aspect | Ounce | Gram |
|---|---|---|
| Family | US/imperial customary unit | SI derived (metric prefix) unit |
| Typical use | US cooking and recipe measurement (small quantities) | Cooking and nutrition labeling worldwide (including in the US, alongside ounces) |
| Where it's used | United States (cooking, postal, retail) | Standard small-mass unit worldwide |
Understanding the Ounce
Ounce (oz) measures mass. The avoirdupois ounce is 1/16 of a pound: exactly 28.349523125 grams. It is classified as a US/imperial customary unit.
Where it's used: United States (cooking, postal, retail) United Kingdom (informal/retail use)
Avoirdupois ounce vs. troy ounce. The everyday ounce (avoirdupois, 28.35 g) used for cooking and shipping is a different, smaller unit than the troy ounce (31.10 g) used for precious metals like gold and silver — this page uses the everyday avoirdupois ounce.
Uses of the Ounce today
- US cooking and recipe measurement (small quantities)
- US postal and shipping weight
- Precious metals (troy ounce, a related but distinct unit)
History of the Ounce
The ounce descends from the Roman 'uncia' (a twelfth part), inherited through medieval English weight systems; the avoirdupois ounce (for general goods, as opposed to the troy ounce for precious metals) became standard for everyday trade, fixed at exactly 28.349523125 g via the pound's 1959 international standardization.
Historical origin. Ounce was not the invention of a single named person; it developed through the process described above.
Understanding the Gram
Gram (g) measures mass. A gram is one-thousandth of a kilogram, the SI base unit of mass. It is classified as a SI derived (metric prefix) unit.
Where it's used: Standard small-mass unit worldwide
Uses of the Gram today
- Cooking and nutrition labeling worldwide (including in the US, alongside ounces)
- Precious metal and small-item weighing
- Scientific and laboratory measurement
History of the Gram
Originally defined in 1795 as the mass of one cubic centimeter of water, the gram follows directly from the kilogram (1/1000 of it) under the modern SI system, inheriting the kilogram's various historical and current definitions.
Historical origin. Gram was not the invention of a single named person; it developed through the process described above.
Ounce — sources
- NIST — International yard and pound (1959) — Basis for the modern ounce via the standardized pound.
Gram — sources
- BIPM — The kilogram (SI base unit) — Basis for the gram as 1/1000 of the kilogram.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many grams are in 1 ounce?
1 ounce equals 28.34952313 grams, using the exact defined conversion factor rather than an estimate.
How do I convert ounce to gram?
Multiply the ounce value by 28.34952313. The converter above does this instantly to whatever precision you set.
How do I convert gram back to ounce?
Use the reverse factor: 1 gram equals 0.035273962 ounces. You can also use the swap control in the converter above to flip the direction instantly.
What is a ounce?
Ounce (oz) measures mass. The avoirdupois ounce is 1/16 of a pound: exactly 28.349523125 grams. It is classified as a US/imperial customary unit.
What is a gram?
Gram (g) measures mass. A gram is one-thousandth of a kilogram, the SI base unit of mass. It is classified as a SI derived (metric prefix) unit.
Is the ounce to gram conversion exact?
Yes. The avoirdupois ounce is 1/16 of a pound: exactly 28.349523125 grams. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between avoirdupois ounce vs. troy ounce?
The everyday ounce (avoirdupois, 28.35 g) used for cooking and shipping is a different, smaller unit than the troy ounce (31.10 g) used for precious metals like gold and silver — this page uses the everyday avoirdupois ounce.
Where is the ounce still used today?
United States (cooking, postal, retail) United Kingdom (informal/retail use)