Convert Ounces to Grains
1 ounce is 437.5 gr. One ounce is exactly 437.5 grains.
One ounce is 437.5 grains. To convert ounces to grains, multiply by 437.5; to go the other way, divide by 437.5 or multiply by 0.0022857143. The factor is exact rather than rounded: it follows from NIST Handbook 44. One sixteenth of a pound.
Factor checked against the defining standard · How we check
- Ounces × 437.5
1 * 437.5437.5 gr
1 ounce in every weight unit
| Unit | Value | Exact factor |
|---|---|---|
| ounces (as entered) | 1 oz | — |
| pounds | 0.0625 lb | × 0.0625 |
| stone | 0.004464285714 st | × 0.00446428571429 |
| US tons | 0.00003125 ton | × 0.00003125 |
| micrograms | 28,349,523.13 mcg | × 28,349,523.125 |
| milligrams | 28,349.52313 mg | × 28,349.523125 |
| centigrams | 2,834.952313 cg | × 2,834.9523125 |
| grams | 28.34952313 g | × 28.349523125 |
| kilograms | 0.02834952313 kg | × 0.028349523125 |
| slugs | 0.001942559386 slug | × 0.00194255938572 |
| tonnes | 0.00002834952313 t | × 0.000028349523125 |
| carats | 141.7476156 ct | × 141.747615625 |
| troy ounces | 0.9114583333 ozt | × 0.911458333333 |
| grains | 437.5 gr | × 437.5 |
| long tons | 0.00002790178571 LT | × 0.0000279017857143 |
Factors are entered by hand from NIST Handbook 44 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert ounces to grains? The converter and the working
- 1.Take the measurement in ounces.
- 2.Multiply by 437.5 — that is how many grains fit in one ounce.
- 3.To go back the other way, divide by 437.5, or multiply by 0.0022857143.
Worked example: 25 ounces to grains
- Formula
- oz × 437.5 = gr
- Arithmetic
- 25 × 437.5 = 10,937.5 gr
- Answer
- 25 oz = 10,937.5 gr
The factor is exact, so this figure is exact too — only the display is rounded.
Ounces to grains conversion table
| Ounces | Grains |
|---|---|
| 1 oz | 437.5 gr |
| 2 oz | 875 gr |
| 3 oz | 1,312.5 gr |
| 4 oz | 1,750 gr |
| 5 oz | 2,187.5 gr |
| 6 oz | 2,625 gr |
| 7 oz | 3,062.5 gr |
| 8 oz | 3,500 gr |
| 9 oz | 3,937.5 gr |
| 10 oz | 4,375 gr |
| 12 oz | 5,250 gr |
| 15 oz | 6,562.5 gr |
| 20 oz | 8,750 gr |
| 25 oz | 10,937.5 gr |
| 50 oz | 21,875 gr |
| 100 oz | 43,750 gr |
| 200 oz | 87,500 gr |
| 300 oz | 131,250 gr |
| 500 oz | 218,750 gr |
| 1000 oz | 437,500 gr |
| 2000 oz | 875,000 gr |
| 5000 oz | 2,187,500 gr |
| 10000 oz | 4,375,000 gr |
What is an ounce?
One sixteenth of a pound. Not to be confused with the fluid ounce, which measures volume.
What is a grain?
Exactly 64.79891 milligrams, the unit both the avoirdupois and troy systems are built from. Bullet weights and powder charges are still measured in it, and so are some pharmaceutical doses.
How many grains are in an ounce?
One ounce is 437.5 grains, exactly. Going the other way, one grain is 0.0022857143 ounces. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every weight unit here
The whole group — 15 units with their symbols and the size of each one in kilograms — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to an ounce.
Cite this page
- APA
- Rule Calculator. (2026). Convert Ounces to grains. Rule Calculator. https://rulecalculators.com/convert/ounce-to-grain
- MLA
- "Convert Ounces to grains." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/ounce-to-grain.
- Chicago
- Rule Calculator. "Convert Ounces to grains." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/ounce-to-grain.
The date is when the figures on this page were last checked against their source, not the day you opened it. Add your own access date if your style needs one.
Questions people actually ask
- How many grains are in an ounce?
- 437.5. Exactly 64.79891 milligrams, the unit both the avoirdupois and troy systems are built from. Bullet weights and powder charges are still measured in it, and so are some pharmaceutical doses.
- How do I convert grains back to ounces?
- Divide by 437.5, or multiply by 0.0022857143 — they are the same operation.
Other weight conversions
Grains to ounces — the same conversion the other way.