Quick Answer: Ounces to Grams
One ounce equals 28.3495231 grams (1 oz = 28.3495231 g).
Conversely, 1 g = 0.0352739619 oz.
Formula: g = oz × 28.349523125
Worked examples
- 1 oz = 28.3495231 g
- 2 oz = 56.6990463 g
- 4 oz = 113.398093 g
Method and limitations
To convert ounces to grams, multiply the ounce value by 28.349523125. One ounce equals approximately 28.35 grams. Calculations use full-precision constants; displayed values are rounded to at most 9 significant figures. Results are rounded for display only. Full precision is kept internally, so long chains of conversions do not accumulate rounding error. Where US customary and imperial units share a name (for example fluid ounces and gallons), this page uses the US customary definition and says so explicitly.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
To convert ounces to grams, multiply the ounce value by 28.349523125. One ounce equals approximately 28.35 grams.
Complete Guide to Ounces to Grams Conversion
What is a Ounces?
The ounce (oz) is a unit of mass in the imperial system. The avoirdupois ounce, used for most food and everyday items, equals exactly 28.349523125 grams. There's also the troy ounce (31.1g) used for precious metals, which is different.
What is a Grams?
The gram (g) is the base unit of mass in the metric system, equal to one-thousandth of a kilogram. It's the global standard for scientific measurements and is preferred in professional cooking for its precision and consistency.
How the Conversion Works
Multiplying ounces by 28.349523125 converts weight from imperial to metric. This factor comes from the 1959 international agreement that defined the avoirdupois pound as exactly 453.59237 grams, making one ounce (1/16 pound) equal to 28.349523125 grams.
Why This Conversion Matters
In baking especially, precision matters. Flour measured by volume can vary by 30% depending on technique, but weighing in grams ensures consistency. Converting ounces to grams lets you use the more accurate measurement system.
Scientific Context
The gram was originally defined as the mass of one cubic centimeter of water at 4°C (its maximum density). Today, the kilogram (1000 grams) is defined by the Planck constant, making it one of the most precisely defined units.
Step-by-Step Conversion Guide
Follow these steps to convert ounces to grams manually:
Start with your value in ounces
Example: You want to convert 4 oz
Apply the conversion formula
Use the formula: g = oz × 28.349523125
Calculate the result
4 oz = 113.3981 g
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
To convert ounces to grams, multiply the ounce value by 28.349523125. One ounce equals approximately 28.35 grams.
Common Conversions
| Ounces (oz) | Grams (g) | Grams → Ounces |
|---|---|---|
| 1 oz | 28.3495 | 1 g = 0.035274 oz |
| 2 oz | 56.699 | 2 g = 0.0705479 oz |
| 4 oz | 113.398 | 4 g = 0.141096 oz |
| 6 oz | 170.097 | 6 g = 0.211644 oz |
| 8 oz | 226.796 | 8 g = 0.282192 oz |
| 10 oz | 283.495 | 10 g = 0.35274 oz |
| 12 oz | 340.194 | 12 g = 0.423288 oz |
| 16 oz | 453.592 | 16 g = 0.564383 oz |
| 24 oz | 680.389 | 24 g = 0.846575 oz |
| 32 oz | 907.185 | 32 g = 1.12877 oz |
Did You Know?
Weight conversions between oz and g are essential in international trade, where different countries use different measurement systems.
This converter is used by thousands of people daily for quick reference. Bookmark it for instant access.
Popular Ounces to Grams Conversions
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When You'll Need This Conversion
Precision Baking
Convert recipe ingredients from American ounces to grams for more accurate and consistent baking results.
International Recipes
Adapt recipes from US cookbooks that use ounces to work with metric kitchen scales.
Nutritional Tracking
Convert food portions to grams for accurate calorie and macro tracking with nutrition apps.
Coffee & Tea Brewing
Specialty coffee recipes often specify beans in grams. Convert from ounce-labeled bags for perfect ratios.
Pro Tips for Accurate Conversions
Invest in a digital kitchen scale
Measuring by weight (grams) is far more accurate than volume. A $20 scale will transform your baking.
Use 28g as your quick reference
For mental math, 1 oz ≈ 28g. This is accurate within 1% and easy to remember.
Weigh ingredients directly into your bowl
Use the tare function to zero out between ingredients. No measuring cups to wash!
Know your butter conversions
1 stick = 4 oz = 113g. Half stick = 2 oz = 57g. This comes up constantly in baking.
Common Mistakes to Avoid
Confusing fluid ounces with weight ounces
Fluid ounces (fl oz) measure volume while ounces (oz) measure weight. A fluid ounce of honey weighs more than a fluid ounce of water.
When a recipe says "4 oz butter," it means weight. When it says "4 fl oz milk," it means volume (½ cup).
Using cup measurements from different countries
A US cup is 237ml, an Australian cup is 250ml, and a Japanese cup is 200ml. This causes recipe failures.
When possible, convert to grams. 1 cup flour ≈ 120-130g (varies by type and how you measure).
Not accounting for ingredient density
One ounce of flour takes up more space than one ounce of sugar because flour is less dense.
Always weigh ingredients when precision matters. A cup of flour can vary by 30% depending on how it's scooped.
History & Background
The ounce has roots in ancient Rome, where the "uncia" was 1/12 of a Roman pound. The gram was created during the French Revolution as part of the metric system, defined as the mass of one cubic centimeter of water.
Key Milestones
Romans used the "uncia" (ancestor of the ounce) as 1/12 of a pound.
The gram was introduced in France as part of the metric system.
The international avoirdupois ounce was defined as exactly 28.349523125 grams.
Professional bakers worldwide began adopting grams for precision.
Home bakers increasingly switched to weighing ingredients in grams for consistency.
Global Usage Today
The gram is used worldwide for cooking and baking precision. Ounces remain common in the US and UK for food packaging and recipes, but professional kitchens globally prefer grams.
Frequently Asked Questions
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Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.