Ounces to Grams Converter
Enter a weight in ounces to get the equivalent in grams, or enter grams to convert back to ounces. Choose between standard avoirdupois ounces (everyday weights, food, shipping) and troy ounces (gold, silver, and other precious metals). The result updates as you type.
Formula
Worked example
8 avoirdupois ounces: 8 × 28.349523125 = 226.796 g. In troy ounces: 8 × 31.1034768 = 248.828 g.
Avoirdupois ounce vs troy ounce
There are two common types of ounce used in weight measurement, and confusing them is a costly mistake. The avoirdupois ounce (abbreviated oz) is the one used in everyday life: food labels, kitchen scales, postal weights, and retail packaging in the United States and United Kingdom. It is equal to exactly 28.349523125 grams, and there are 16 avoirdupois ounces in a pound. The troy ounce (abbreviated oz t or ozt) is heavier at 31.1034768 grams, roughly 10 percent more than a standard ounce. It is the international standard for weighing precious metals including gold, silver, platinum, and palladium, as well as gemstones. There are only 12 troy ounces in a troy pound, which means a troy pound (373.24 g) is actually lighter than an avoirdupois pound (453.59 g). Always verify which ounce type is intended before calculating, especially when dealing with metal trading or jewelry.
How to convert ounces to grams
To convert avoirdupois ounces to grams, multiply the number of ounces by 28.349523125. For example, 5 oz times 28.349523125 equals 141.748 grams. To convert troy ounces to grams, multiply by 31.1034768 instead: 5 troy oz times 31.1034768 equals 155.517 grams. Going the other way, divide the gram value by the appropriate factor: 500 g divided by 28.349523125 gives about 17.637 avoirdupois ounces, and 500 g divided by 31.1034768 gives about 16.075 troy ounces. This calculator handles both directions and both ounce types automatically, so you only need to enter the value and choose the mode.
Weight ounce vs fluid ounce
A weight ounce (oz) and a fluid ounce (fl oz) are completely different units that happen to share a name. A weight ounce measures mass, while a fluid ounce measures volume. For water at room temperature, 1 US fluid ounce is about 29.574 mL and weighs about 29.57 grams, which is close to but not equal to one avoirdupois ounce. The difference becomes more pronounced for denser or lighter liquids. For example, 1 fl oz of olive oil weighs about 27.2 grams, while 1 fl oz of honey weighs about 42.5 grams. When a recipe says "1 oz" of a liquid, it usually means a fluid ounce measured by volume, not a weight ounce measured by mass. Use a scale for weight conversions and a measuring cup for volume.
Common uses and real-world examples
Knowing exact gram equivalents matters in several everyday situations. In cooking and baking, US recipes often list ingredients in ounces while metric recipes use grams. A standard stick of butter in the US is 4 oz, which is 113.4 grams. A cup of all-purpose flour is typically 4.25 oz, or about 120.5 grams. In postal and shipping contexts, the USPS rates mail by the ounce, and international labels may require grams. A First-Class letter up to 1 oz can weigh no more than 28.35 grams. In health and fitness, protein powder and supplement servings are often given in grams, so knowing how many grams are in a scoop described as "1 oz" is useful. For precious metals, gold prices are quoted per troy ounce, so converting a bar listed in grams to troy ounces tells you the spot value.
Ounces to Grams Conversion Table (Avoirdupois)
| Ounces (oz) | Grams (g) | Kilograms (kg) |
|---|---|---|
| 0.25 | 7.09 | 0.00709 |
| 0.5 | 14.17 | 0.01417 |
| 1 | 28.35 | 0.02835 |
| 2 | 56.70 | 0.05670 |
| 4 | 113.40 | 0.11340 |
| 8 | 226.80 | 0.22680 |
| 12 | 340.19 | 0.34019 |
| 16 | 453.59 | 0.45359 |
| 32 | 907.19 | 0.90719 |
| 100 | 2834.95 | 2.83495 |
| 1000 | 28349.52 | 28.34952 |
Quick-reference conversions using the standard avoirdupois ounce (1 oz = 28.3495 g), rounded to 2 decimal places.
Frequently asked questions
How many grams are in one ounce?
One avoirdupois ounce (the standard ounce used for food, shipping, and everyday weights) equals exactly 28.349523125 grams. One troy ounce (used for precious metals) equals 31.1034768 grams. When someone says "one ounce" without specifying, they almost always mean the avoirdupois ounce.
How many ounces are in a gram?
One gram equals approximately 0.035274 avoirdupois ounces, or about 0.032151 troy ounces. To find the number of ounces, divide the gram value by 28.349523125 (avoirdupois) or 31.1034768 (troy).
What is the difference between a troy ounce and a regular ounce?
A troy ounce weighs 31.1034768 grams, while a regular (avoirdupois) ounce weighs 28.349523125 grams. That means a troy ounce is about 9.7 percent heavier. Troy ounces are used exclusively for precious metals and gemstones. If you are not dealing with gold, silver, platinum, or gems, use the avoirdupois ounce.
How do I convert 8 ounces to grams?
Multiply 8 by 28.349523125 to get 226.796 grams (avoirdupois). If you mean troy ounces, multiply 8 by 31.1034768 to get 248.828 grams. Eight avoirdupois ounces is also half a pound (453.59 g / 2 = 226.80 g).
Is 100 grams equal to 4 ounces?
Close but not exact. 100 grams equals about 3.527 avoirdupois ounces. Four avoirdupois ounces equals about 113.4 grams. The rough "100 g is about 3.5 oz" rule of thumb is useful for quick estimates but not for precise measurements.
Why are precious metals weighed in troy ounces?
The troy system dates back to medieval European trade, particularly the Troyes market in France, where international merchants standardized weights for precious commodities. When national weight standards evolved into the modern avoirdupois system for everyday goods, precious metals retained the older troy standard. Today, global commodity exchanges including the London Metal Exchange and the COMEX quote gold and silver prices per troy ounce.