This converter turns grains into stones instantly, using the exact factor 1 grain = 1.020408163e-05 stones. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
The oldest English mass unit, now used for bullets, arrows and propellant charges. Fourteen pounds — still the customary way to state body weight in the UK and Ireland.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
grains- The amount you are converting, measured in grains
1.020408163e-05- The exact number of stones in one grain
stones- The converted result
How it works, step by step
- Enter the number of grains you want to convert.
- The value is multiplied by 1.020408163e-05, the exact conversion factor.
- The result is displayed in stones, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 grains
Multiply 5 by 1.0204082e-05. That gives 0.000051 stones. A quick sanity check: one grain is smaller than one stone, so the number should get smaller — and it does.
Converting 72 grains
72 × 1.0204082e-05 = 0.000735 stones. Working backwards, 0.000735 ÷ 1.0204082e-05 returns 72 grains, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many stones are in one grain?
Exactly 1.020408163e-05. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert grains to stones?
Stones = grains × 1.020408163e-05. To reverse it, divide instead: grains = stones ÷ 1.020408163e-05, which is the same as multiplying by 98000.
Is the grain bigger than the stone?
No. One grain is only 1.02041e-05 of a stone, so the stone is the larger unit.
Why does my answer differ slightly from other grains to stones converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a grain?
The oldest English mass unit, now used for bullets, arrows and propellant charges.
What is a stone?
Fourteen pounds — still the customary way to state body weight in the UK and Ireland.
Grains to stones reference table
| Grains | Stones |
|---|---|
| 0.5 gr | 0.000005 st |
| 1 gr | 0.00001 st |
| 2 gr | 0.00002 st |
| 3 gr | 0.000031 st |
| 5 gr | 0.000051 st |
| 10 gr | 0.000102 st |
| 15 gr | 0.000153 st |
| 20 gr | 0.000204 st |
| 25 gr | 0.000255 st |
| 50 gr | 0.00051 st |
| 75 gr | 0.000765 st |
| 100 gr | 0.00102 st |
| 250 gr | 0.002551 st |
| 500 gr | 0.005102 st |
| 1000 gr | 0.010204 st |
Exact factor: 1 grain = 1.020408163e-05 stones. Values rounded for display.