Ounces to Grams Converter
The Formula
Common Ounces to Grams Values
| Ounces | Grams | Fraction |
|---|---|---|
| 0.25 | 7.09 | 7⅛ |
| 0.5 | 14.18 | 14⅛ |
| 0.75 | 21.26 | 21¼ |
| 1 | 28.35 | 28⅓ |
| 1.5 | 42.53 | 42½ |
| 2 | 56.70 | 56⅔ |
| 3 | 85.05 | 85⅛ |
| 4 | 113.40 | 113⅜ |
| 5 | 141.75 | 141¾ |
| 8 | 226.80 | 226¾ |
| 10 | 283.50 | 283½ |
| 12 | 340.20 | 340¼ |
A Worked Example
A recipe calls for 6 ounces of chocolate. Multiply 6 by 28.35 to get 170.1 grams — a figure that matches almost exactly to a standard 170g chocolate bar sold in many grocery stores.
When This Conversion Matters
This is a weight-to-weight conversion, so it stays constant no matter what ingredient you're measuring.
It's the most common conversion for packaged ingredients labeled in ounces on US grocery products.
Meat and produce sold by the pound and ounce at US grocery stores frequently need converting when following a recipe written with metric weights, especially for imported or translated cookbooks.
Coffee roasting and brewing, a hobby where precision by weight matters significantly, commonly requires converting between the ounce measurements on US bag labels and the gram measurements used by most brewing scales and recipes.
Import and export documentation for food products crossing between the US and metric-using countries frequently requires both weight figures listed side by side, making this conversion a routine part of international food trade paperwork.
Standards and Sources
The international avoirdupois ounce, used for food weight in the US, is defined as exactly 28.349523125 grams — commonly rounded to 28.35g, per international standards agreements dating to 1959.
This is distinct from the troy ounce (31.1g), used for precious metals, a frequent point of confusion since both share the name 'ounce' but represent different standardized weights.
USDA FoodData Central lists both gram and ounce weights for its ingredient database, using the 28.35g avoirdupois standard consistently across its US food data.
The Federal Trade Commission's Fair Packaging and Labeling Act requires US consumer products to display both customary (ounces/pounds) and, where applicable, metric weight, which is part of why grocery packaging often shows both units side by side.
Where This Unit Comes From
The avoirdupois ounce traces to medieval French and English trade weight systems, formally fixed to the metric gram in a 1959 international agreement between the US and Commonwealth countries to eliminate small historical discrepancies between national standards.
Where This Shows Up
US grocery products, from cheese to deli meat, are commonly priced and labeled by the ounce, and shoppers following a recipe with metric ingredient weights rely on this conversion to buy the right quantity.
Coffee roasting and brewing at home, a hobby where gram-level precision matters significantly, frequently requires converting between the ounce measurements on US bag labels and the gram measurements used by brewing scales and recipes.
Home soap-making and candle-making, hobbies where precise ingredient ratios affect the final product's texture and burn quality, frequently require converting between ounce-labeled supplies and gram-based recipe formulas.
Specialty tea and coffee retailers selling by weight often list product sizes in both ounces and grams on packaging, helping international customers compare value regardless of which unit they think in.
Common Mistakes
- Confusing the weight ounce (28.35g) with the fluid ounce (a volume unit), especially when a recipe lists a liquid ingredient 'by the ounce.'
- Using the troy ounce figure (31.1g) instead of the standard avoirdupois ounce for food conversions.
- Rounding 28.35 down to a flat 28 for a large batch, which introduces meaningful error as the ounce quantity increases.
- Confusing a product's 'net weight' ounce figure with its total packaged weight, which includes container weight and won't match the ingredient conversion alone.
Avoirdupois Ounce vs Troy Ounce
| Avoirdupois Ounce (Food) | Troy Ounce (Precious Metals) | |
|---|---|---|
| Weight | 28.35 g | 31.1 g |
| Used for | Food, everyday goods | Gold, silver, gemstones |
| Ounces per pound | 16 | 12 |
Related Converters
Frequently Asked Questions
How many grams are in an ounce?+
28.35 grams make 1 ounce, for any substance.
Is this the same as a fluid ounce conversion?+
No. Fluid ounces measure volume, while this converts weight ounces to grams.
How many grams are in 8 ounces?+
About 227 grams.
Is a troy ounce the same as a food ounce?+
No. A troy ounce (31.1g), used for precious metals, is heavier than the standard avoirdupois ounce (28.35g) used for food and everyday goods.
Why do US recipes still use ounces instead of grams?+
Ounces remain the customary US standard for packaged food, even though grams are more precise and used almost everywhere else.
Is this conversion different for liquids versus solids?+
No, as long as you're using the weight ounce for both. Liquids measured by weight convert the same way as solids.
Do all countries use the same definition of 'ounce'?+
The avoirdupois ounce (28.35g) is used in the US, UK, and most English-speaking countries for food, though the troy ounce remains separately defined for precious metals globally.