Troy Ounce Converter
Convert troy ounces, pennyweights, grains, grams, and kilos.
What it does
Troy weight prices precious metals: 20 pennyweights or 480 grains make one troy ounce of 31.1034768 grams. Kitchen ounces run lighter at 28.35 g, so mixing the two shorts every gold deal by nearly 10%.
The tool above converts between troy ounces, pennyweights, grains, grams, kilos, and regular ounces. Pick both ends, enter the value, and every equivalent appears below.
The default 1 ozt reads 31.1035 g (20 dwt, 480 grains). Reversing 100 g gives 3.2151 ozt, the number a scrap buyer divides into.
Factors follow NIST precious metals conversion references with US Mint coin specifications matching them. Both fix the troy ounce at 31.1034768 g against the 28.35 g everyday ounce.
How to use
- Enter the weight value.
- Pick the source unit on the left and the target on the right.
- Read the converted line first.
- Scan the all units note for the rest.
- Price metals per ozt unless the quote says grams.
Formula
- 31.1034768
- Grams in one troy ounce.
- 20 / 480
- Pennyweights and grains per ozt.
- hub
- Grams as the single middle step.
Karat purity sits outside weight math: 18k holds 75% gold by weight, so multiply metal weight by fineness for pure content.
Worked example
Example: 1 ozt to grams
Value 1, from troy ounces, to grams.
- Factor: 31.1034768 g per ozt.
- Multiply: 1 x 31.1034768 = 31.1034768 g.
- Round to four places: 31.1035 g.
- Check: 20 dwt x 1.55517384 = 31.1035 g back.
- Result: 1 ozt = 31.1035 g.
Reference table
| Unit | In grams | Per ozt |
|---|---|---|
| Grain | 0.06479891 | 480 |
| Pennyweight | 1.55517384 | 20 |
| Troy ounce | 31.1034768 | 1 |
| Avoirdupois oz | 28.34952313 | 0.9115 ozt |
Limits
- Weight only; karat purity needs fineness math.
- Buyer scales and fees sit outside.
- Gem carats (0.2 g) differ from gold karats.
- Spot prices move intraday past any table.
Common mistakes
- Weighing gold in kitchen ounces (10% light).
- Reading grams as ozt on foreign listings.
- Forgetting karat fineness on alloy weight.
- Rounding mid chain across conversions.
- Trusting shop scales without calibration.
Try it yourself
Quick checks. Answers sit tucked under each question.
100 g in ozt?
100 / 31.1034768 = 3.2151 ozt.
6.85 dwt price at $59.10 per dwt?
6.85 x 59.10 = $404.84 (NIST example).
1 kg in ozt?
1000 / 31.1034768 = 32.1507 ozt.
Questions
How many grams in a troy ounce?
31.1034768 g: 20 dwt or 480 grains.
Troy vs regular ounce?
Troy 31.10 g beats kitchen 28.35 g by nearly 10%.
What is a pennyweight?
1/20 ozt (1.555 g), the jewelry trade unit.
What is a grain?
1/480 ozt (0.0648 g), also the bullet reloading unit.
Why troy for gold?
Centuries of bullion custom, fixed by weights law.
Does karat change weight?
No, only pure content: 18k holds 75% of the weight as gold.