Ounces to Grams
Troy ounces, regular ounces, grams, pennyweight and kilograms
1 ounce is 28.35 grams. 1 troy ounce, the ounce used for gold and silver, is 31.10 grams.
ounces to grams
- 1 oz
- 28.349523 g
- 1 g
- 0.035274 oz
How it works
- 1 troy ounce = 31.1035 g = 20 dwt = 1.0971 oz = 0.0311 kg.
- 1 oz × 28.34952 g per oz = 28.3495 g.
ounces to grams 28.3495 g
How many grams in each unit
| Unit | Grams |
|---|---|
| 1 gram | 1 |
| 1 ounce (avoirdupois) | 28.3495 |
| 1 troy ounce | 31.1035 |
| 1 pennyweight (dwt) | 1.5552 |
| 1 grain | 0.06480 |
| 1 pound (avoirdupois) | 453.5924 |
| 1 kilogram | 1,000 |
Troy ounce vs regular ounce
There are two ounces. The regular ounce, called the avoirdupois ounce, is 28.3495 g. It is the one on a kitchen scale and a package label. The troy ounce is 31.1035 g, about 10% heavier. A troy ounce is 480 grains and a regular ounce is 437.5 grains.
Precious metals use the troy ounce. When a site says gold is $4,000 an ounce, that is per troy ounce. A coin sold as "1 oz" of gold or silver holds one troy ounce, 31.1035 g, not 28.3495 g.
The units also stack up differently. A troy pound is 12 troy ounces (373.24 g). A regular pound is 16 regular ounces (453.59 g). Nobody sells bullion by the troy pound today, but the old unit explains why the two ounces differ.
Rule of thumb: troy ounces times 31.1 gives grams. Regular ounces times 28.35 gives grams. Grams divided by 31.1 gives troy ounces.
Bullion weights in grams, troy ounces and ounces
| Item | Grams | Troy oz |
|---|---|---|
| 1/10 oz gold coin | 3.110 | 0.1000 |
| 1/4 oz gold coin | 7.776 | 0.2500 |
| 1/2 oz gold coin | 15.552 | 0.5000 |
| 1 oz coin or round (Eagle, Maple Leaf) | 31.103 | 1.0000 |
| 5 oz silver bar | 155.517 | 5.0000 |
| 10 oz bar | 311.035 | 10.0000 |
| 100 g bar | 100.000 | 3.2151 |
| 1 kg bar | 1,000.000 | 32.1507 |
| 100 oz silver bar | 3,110.348 | 100.0000 |
A "1 kilo" bar is 1,000 g, which is 32.1507 troy ounces, so it holds more than 32 times what a 1 oz coin holds. A "10 oz" bar is 10 troy ounces, 311.035 g.
Ounces to grams, both kinds
| Ounces | Regular oz in grams | Troy oz in grams |
|---|---|---|
| 0.25 | 7.087 | 7.776 |
| 0.5 | 14.175 | 15.552 |
| 1 | 28.350 | 31.103 |
| 2 | 56.699 | 62.207 |
| 5 | 141.748 | 155.517 |
| 10 | 283.495 | 311.035 |
| 16 | 453.592 | 497.656 |
| 32.15 | 911.437 | 999.977 |
| 100 | 2,834.952 | 3,110.348 |
Worked example. A 5 troy ounce silver bar: 5 x 31.1035 = 155.517 g. A 5 regular ounce package: 5 x 28.3495 = 141.748 g. Same number, different weight.
Source: NIST Special Publication 811, Appendix B (exact conversion factors: 1 avoirdupois ounce = 28.349523125 g, 1 troy ounce = 31.1034768 g, 1 grain = 0.06479891 g). Weights of bars are the nominal weights named on the bar.
Troy ounces to ounces Pennyweight to grams Gold price per gram Silver price per gram Scrap silver calculator
How this calculator works
How many grams are in an ounce?
A regular (avoirdupois) ounce is 28.3495 grams. A troy ounce, the one used for gold and silver, is 31.1035 grams.
How many grams are in an ounce of gold?
An ounce of gold is a troy ounce: 31.1035 grams. Silver, platinum and palladium use the same ounce.
Is a troy ounce heavier than a regular ounce?
Yes. A troy ounce is 31.1035 g and a regular ounce is 28.3495 g, so the troy ounce is about 9.7% heavier.
How do I convert ounces to grams?
Multiply the ounces by 28.3495 for regular ounces, or by 31.1035 for troy ounces. For example, 3 regular ounces is 85.05 g and 3 troy ounces is 93.31 g.
How many ounces is 100 grams?
100 grams is 3.5274 regular ounces or 3.2151 troy ounces.
