Oz to Grams Converter
Result
28.3495 grams
Also Equal To
How Ounces to Grams Conversion Works
An ounce-to-gram conversion translates a mass measurement from the Imperial/US customary ounce into the metric gram, the base unit of mass in the International System of Units (SI). According to the International Bureau of Weights and Measures (BIPM), the kilogram (and by extension the gram) was redefined in 2019 in terms of the Planck constant, making it one of the most precisely defined units in science.
The standard avoirdupois ounce -- used for food, mail, and everyday weighing -- equals exactly 28.349523125 grams. This conversion factor is defined by the National Institute of Standards and Technology (NIST) and is internationally agreed upon. Over 95% of the world's countries use grams and kilograms as their primary mass units, making this conversion essential for international trade, cooking, and shipping.
Cooks converting American or British recipes to metric, jewelers weighing precious metals, postal workers calculating shipping costs, and nutritionists converting food labels all rely on this conversion. Our Grams to Oz Converter handles the reverse direction, and the Weight Converter supports all major weight units.
The Oz to Grams Formula
The formula depends on which ounce type you are converting:
Grams = Ounces x Conversion Factor
- Avoirdupois ounce: 1 oz = 28.349523125 g (standard everyday ounce)
- Troy ounce: 1 oz t = 31.1034768 g (precious metals only)
Worked example: A recipe calls for 12 oz of chocolate chips. Converting: 12 x 28.3495 = 340.2 grams. At the store, you would buy a 340 g or 350 g bag of chocolate chips. The formula is standardized by the international yard and pound agreement of 1959, which defined 1 pound = 0.45359237 kg exactly.
Key Terms You Should Know
- Avoirdupois Ounce -- The standard ounce used in the US and UK for everyday weighing. Equal to 28.3495 grams or 1/16 of an avoirdupois pound. This is the ounce used on food packaging, postal scales, and kitchen scales.
- Troy Ounce -- A heavier ounce (31.1035 g) used exclusively for precious metals like gold, silver, and platinum. Named after the French market city of Troyes. There are 12 troy ounces per troy pound, not 16.
- Gram (g) -- The base metric unit of mass, equal to 1/1000 of a kilogram. Defined since 2019 by the Planck constant. Used worldwide in science, medicine, cooking, and commerce.
- Fluid Ounce (fl oz) -- A volume measure (29.5735 mL), not a weight measure. Often confused with weight ounces. One fluid ounce of water weighs approximately 29.57 grams, close to but not exactly 1 oz (28.35 g).
- Pound (lb) -- Equal to 16 avoirdupois ounces or 453.592 grams. The conversion between pounds and grams can be derived from the oz-to-grams factor: 16 x 28.3495 = 453.592 g.
Ounces to Grams Conversion Table
Common ounce-to-gram conversions based on the NIST standard factor of 28.349523125 grams per avoirdupois ounce.
| Ounces | Grams | Kilograms |
|---|---|---|
| 0.5 oz | 14.17 | 0.014 |
| 1 oz | 28.35 | 0.028 |
| 2 oz | 56.70 | 0.057 |
| 4 oz | 113.40 | 0.113 |
| 6 oz | 170.10 | 0.170 |
| 8 oz (1/2 lb) | 226.80 | 0.227 |
| 12 oz | 340.19 | 0.340 |
| 16 oz (1 lb) | 453.59 | 0.454 |
| 32 oz (2 lb) | 907.18 | 0.907 |
Practical Examples
Converting a steak weight for a European recipe: You have a 10 oz ribeye steak. Converting: 10 x 28.3495 = 283.5 grams. A European recipe calling for a 300 g steak portion would require a slightly larger cut -- about 10.6 oz. Use our Calorie Calculator to estimate the nutritional content.
Gold investment calculation: Gold is priced at $2,350 per troy ounce. You want to know the per-gram price: $2,350 / 31.1035 = $75.56 per gram. Note that if you mistakenly used the avoirdupois ounce (28.3495 g), you would calculate $82.93 per gram -- a 9.7% overestimate. The troy ounce distinction matters significantly in precious metals.
Shipping package weight: A package weighs 14 oz on your postal scale. For an international label in grams: 14 x 28.3495 = 396.9 grams. This falls under the 500 g category for most international postal rates. Use our Weight Converter for pounds and kilograms.
Tips for Accurate Oz to Grams Conversion
- Use 28.35 for quick estimates: Rounding from 28.3495 to 28.35 introduces less than 0.02% error, which is negligible for all practical purposes including baking.
- Always clarify troy vs avoirdupois: If converting precious metal weights, use 31.1035 g per troy ounce, not 28.3495 g. The 9.7% difference can mean hundreds of dollars per ounce at current gold prices.
- Do not confuse fluid ounces with weight ounces: A recipe saying "8 oz of cream cheese" means weight (226.8 g). A recipe saying "8 fl oz of milk" means volume (236.6 mL). Context usually clarifies, but when in doubt, check whether the ingredient is a liquid or solid.
- Use a digital scale for precision: Kitchen scales accurate to 1 gram cost $10-20 and eliminate conversion errors. For baking, a scale accurate to 0.1 grams ($20-40) is ideal for small quantities like yeast and salt.
- Remember key benchmarks: 4 oz = 113 g (a standard US stick of butter is 4 oz or 113 g), 8 oz = 227 g (half a pound), 16 oz = 454 g (one pound). These anchors make mental estimation easier.
The International Yard and Pound Agreement
The exact oz-to-gram conversion factor traces back to the 1959 International Yard and Pound Agreement, signed by the US, UK, Canada, Australia, New Zealand, and South Africa. This agreement defined the avoirdupois pound as exactly 0.45359237 kilograms, from which the ounce derives: 453.59237 / 16 = 28.349523125 grams per ounce. Before 1959, different countries used slightly different definitions of the pound, creating small but measurable discrepancies in international trade. The agreement eliminated these differences, establishing the internationally consistent conversion factors used today by NIST and equivalents worldwide.
Frequently Asked Questions
How many grams are in 1 ounce?
One avoirdupois ounce equals exactly 28.349523125 grams. This is the standard ounce used in everyday cooking, grocery shopping, and postal weighing in the United States and United Kingdom. The conversion factor is internationally defined and maintained by the International Bureau of Weights and Measures (BIPM). For quick mental math, 1 oz is approximately 28.35 grams. A troy ounce, used for precious metals, is heavier at 31.1035 grams. Always verify which ounce type is being referenced.
What is the difference between a troy ounce and a regular ounce?
A troy ounce equals 31.1035 grams while a regular (avoirdupois) ounce equals 28.3495 grams -- the troy ounce is about 9.7% heavier. Troy ounces are used exclusively for precious metals like gold, silver, and platinum. When gold is quoted at $2,000 per ounce, that means per troy ounce. The troy system dates back to the medieval French city of Troyes, a major trading center. There are 12 troy ounces in a troy pound (373.2 g), versus 16 avoirdupois ounces in a regular pound (453.6 g).
How do I convert 8 oz to grams?
8 avoirdupois ounces equals approximately 226.8 grams. The calculation is 8 multiplied by 28.3495 = 226.796 grams. Note that 8 oz is also equal to half a US pound (0.5 lb). In cooking, 8 oz by weight is a common measurement -- for example, an 8 oz block of cream cheese weighs 226.8 grams. Do not confuse weight ounces with fluid ounces: 8 fluid ounces is a volume measurement equal to 1 US cup (236.6 mL), not a weight measurement.
How many ounces is 100 grams?
100 grams equals approximately 3.527 ounces. To convert grams to ounces, divide by 28.3495: 100 / 28.3495 = 3.5274 oz. The 100-gram measurement is extremely common in nutrition labeling worldwide -- the EU requires nutritional information per 100 grams on all food packaging. In the US, this is roughly 3.5 ounces. For a quick approximation, divide grams by 30 to estimate ounces (100 / 30 = 3.33 oz, within 5.5% of the exact value).
Is a fluid ounce the same as an ounce by weight?
No, a fluid ounce and a weight ounce are completely different measurements. A fluid ounce (fl oz) measures volume and equals 29.5735 mL. A weight ounce (oz) measures mass and equals 28.3495 grams. They happen to be nearly equivalent for water at room temperature (1 fl oz of water weighs approximately 1.043 oz), which causes frequent confusion. For honey, 1 fl oz weighs about 1.5 oz due to higher density. For cooking oil, 1 fl oz weighs about 0.95 oz. Always specify whether a recipe means fluid ounces or weight ounces.
How do I convert ounces to grams for baking?
For baking, multiply the number of ounces by 28.35 to get grams. For example, a recipe calling for 6 oz of chocolate converts to 6 x 28.35 = 170.1 grams. Professional bakers prefer grams because they allow more precise measurements -- a difference of even 5 grams of leavening agent can noticeably affect a cake's rise. According to the King Arthur Baking Company, weighing ingredients in grams reduces batch-to-batch variation by up to 25% compared to volume measurements.