Precious Metal Weights & Conversions
Glossary & Reference
Precious metals use specific weight measurements that differ from everyday units. This guide helps you understand and convert between these units.
Troy Weight System
Precious metals are measured in troy weight, not the avoirdupois (everyday) system:
Troy Units
| Unit | Grams | Troy Ounces |
|---|---|---|
| 1 Troy Ounce | 31.1035 g | 1.000 |
| 1 Pennyweight (dwt) | 1.5552 g | 0.050 |
| 1 Troy Pound | 373.2417 g | 12.000 |
| 1 Grain | 0.0648 g | 0.002 |
Troy vs. Avoirdupois
| Troy | Avoirdupois |
|---|---|
| 1 troy oz = 31.1 g | 1 regular oz = 28.35 g |
| 1 troy lb = 12 troy oz | 1 regular lb = 16 oz |
Important: A troy ounce is about 10% heavier than a regular ounce!
Quick Conversion Formulas
- Grams to Troy Oz: grams ÷ 31.1035
- Troy Oz to Grams: troy oz × 31.1035
- Pennyweights to Grams: dwt × 1.5552
- Grams to Pennyweights: grams ÷ 1.5552
- Troy Oz to Pennyweights: troy oz × 20
Common Bullion Sizes
Gold
| Size | Troy Oz | Grams |
|---|---|---|
| 1 gram bar | 0.032 | 1.00 |
| 1/10 oz coin | 0.100 | 3.11 |
| 1/4 oz coin | 0.250 | 7.78 |
| 1/2 oz coin | 0.500 | 15.55 |
| 1 oz coin/bar | 1.000 | 31.10 |
| 10 oz bar | 10.000 | 311.03 |
| 1 kilo bar | 32.151 | 1,000.00 |
| 400 oz Good Delivery | ~400 | ~12,441 |
Silver
| Size | Troy Oz | Grams |
|---|---|---|
| 1 oz coin/bar | 1.000 | 31.10 |
| 10 oz bar | 10.000 | 311.03 |
| 100 oz bar | 100.000 | 3,110.35 |
| 1,000 oz commercial bar | ~1,000 | ~31,103 |
Jewelry Weight Context
- Average wedding band: 3-6 grams
- Average engagement ring: 2-4 grams (metal only)
- Heavy men's ring: 8-15 grams
- Typical chain necklace: 5-20 grams
Calculating Metal Value
Formula: (Weight in grams ÷ 31.1035) × Spot Price × Purity = Metal Value
Example: 10g of 14K gold at $2,000/oz spot:
(10 ÷ 31.1035) × $2,000 × 0.583 = $375.02
BigStash.app performs these calculations automatically when you enter item weights and purity.