This converter turns grains into carats instantly, using the exact factor 1 grain = 0.32399455 carats. 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. Exactly 200 milligrams — the mass unit for gemstones and pearls.
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
0.32399455- The exact number of carats in one grain
carats- The converted result
How it works, step by step
- Enter the number of grains you want to convert.
- The value is multiplied by 0.32399455, the exact conversion factor.
- The result is displayed in carats, 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 0.32399455. That gives 1.62 carats. A quick sanity check: one grain is smaller than one carat, so the number should get smaller — and it does.
Converting 72 grains
72 × 0.32399455 = 23.3276 carats. Working backwards, 23.3276 ÷ 0.32399455 returns 72 grains, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many carats are in one grain?
Exactly 0.32399455. 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 carats?
Carats = grains × 0.32399455. To reverse it, divide instead: grains = carats ÷ 0.32399455, which is the same as multiplying by 3.086471671.
Is the grain bigger than the carat?
No. One grain is only 0.323995 of a carat, so the carat is the larger unit.
Why does my answer differ slightly from other grains to carats 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 carat?
Exactly 200 milligrams — the mass unit for gemstones and pearls.
Grains to carats reference table
| Grains | Carats |
|---|---|
| 0.5 gr | 0.161997 ct |
| 1 gr | 0.323995 ct |
| 2 gr | 0.647989 ct |
| 3 gr | 0.971984 ct |
| 5 gr | 1.62 ct |
| 10 gr | 3.2399 ct |
| 15 gr | 4.8599 ct |
| 20 gr | 6.4799 ct |
| 25 gr | 8.0999 ct |
| 50 gr | 16.1997 ct |
| 75 gr | 24.2996 ct |
| 100 gr | 32.3995 ct |
| 250 gr | 80.9986 ct |
| 500 gr | 161.9973 ct |
| 1000 gr | 323.9945 ct |
Exact factor: 1 grain = 0.32399455 carats. Values rounded for display.