How Many Grams in an Ounce
A grams-in-an-ounce page converts weight metrics between imperial ounces and metric grams. In the standard Avoirdupois system, 1 ounce equals exactly 28.3495 grams. In the Troy system, used for gold and silver, 1 ounce equals exactly 31.1035 grams. The page assists with cooking, food labeling, and bullion weight conversions.
Convert between ounces and grams instantly. Understand the differences between standard avoirdupois ounces and troy ounces, and use our reference tables.
Quick Answer
Find out exactly how many grams are in a standard ounce (28.35 grams) or a precious metal troy ounce (31.10 grams).
How Many Grams in an Ounce?
There are 28.35 grams in a standard ounce.
For precious metals, a troy ounce contains exactly 31.10 grams.
Ounce Measurement Standard
Formula: 1 Ounce = 28.3495 grams (Avoirdupois Ounce (Standard))
Ounces to Grams Conversion Table
| Ounces (oz) | Standard Grams (g) | Troy Grams (g) |
|---|---|---|
| 0.1 oz | 2.83 g | 3.11 g |
| 0.25 oz (1/4 oz) | 7.09 g | 7.78 g |
| 0.5 oz (1/2 oz) | 14.17 g | 15.55 g |
| 1 oz | 28.35 g | 31.10 g |
| 2 oz | 56.70 g | 62.21 g |
| 4 oz (1/4 lb) | 113.40 g | 124.41 g |
| 8 oz (1/2 lb) | 226.80 g | 248.83 g |
| 16 oz (1 lb) | 453.59 g | 497.66 g |
Examples
1 Ounce (Standard)
28.35 g
1 Ounce (Troy)
31.10 g
16 Ounces (1 lb)
453.59 g
How it works
The standard unit of mass in the US customary system is the avoirdupois ounce, which relates to the metric gram as follows:
Standard Mass Conversion
1 Ounce (oz) = 28.3495 Grams (g)
Conversion Formula
Multiply ounces by 28.3495 to convert to grams. Divide grams by 28.3495 to convert to ounces.
Standard Ounces vs. Troy Ounces
There are two distinct weight standards that use the term "ounce". Confusing them can lead to costly errors:
- Avoirdupois Ounce (oz): This is the standard grocery and postal ounce. There are 16 of these ounces in a standard pound. One avoirdupois ounce equals 28.35 grams.
- Troy Ounce (ozt): This unit is used exclusively for precious metals like gold, silver, and platinum. There are 12 troy ounces in a troy pound. One troy ounce equals 31.10 grams.
Because a troy ounce is about 9.7% heavier than a standard ounce, gold bullion is always traded and priced using the heavier 31.10-gram troy ounce standard.
FDA Food Labeling & Kitchen Rounding
In culinary school and home kitchens, recipes requiring high precision (like baking bread or scaling spices) rely on weight measurements. While a standard ounce is technically 28.35 grams, cooks usually round it to 28 grams for convenience.
Similarly, the FDA allows food manufacturers to round serving sizes. A single serving of chips or nuts that weighs 1 ounce will show "28g" on the nutrition facts panel rather than the precise "28.35g".
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