Convert grains to carats

1 gr=0.324ct

Use the converter below to change any grains value into carats instantly — with formula, conversion table, and real-world examples.

You have

Equals

0.32399

Conversion formula

Forward

carats = grains × 0.324

Reverse

grains = carats × 3.08647

Example: 10 gr × 0.324 = 3.23995 ct.

About both units

From

Grain

The grain equals 64.79891 milligrams exactly, one of the oldest units of mass. Originally defined as the weight of a single grain of barley. Today used almost exclusively in firearms (bullet and gunpowder weights) and pharmaceuticals.

Real-world: A 9 mm bullet typically weighs 115–124 grains (7.45–8.03 g). Aspirin grain dosing: "5 grain aspirin" = 325 mg.

Read full grain reference →

Carat

The metric carat equals 200 milligrams exactly. It is the standard unit for gemstone weight — diamonds, rubies, sapphires and emeralds are sold by the carat. Do not confuse with the purity carat (karat) used for gold (24K = pure gold).

Real-world: A 1-carat diamond weighs 200 mg and is typically 6.5 mm across. The Hope Diamond is 45.52 carats (9.1 g).

Read full carat reference →

Grain to Carat conversion table

Common grains to carats values for quick reference.

Grain (gr)	Carat (ct)
1 gr	0.324 ct
5 gr	1.61997 ct
10 gr	3.23995 ct
25 gr	8.09986 ct
50 gr	16.1997 ct
100 gr	32.3995 ct
250 gr	80.9986 ct
500 gr	161.997 ct
1,000 gr	323.995 ct
5,000 gr	1,619.97 ct

Tips & common mistakes

Quick tips

1 grain = 64.79891 mg exactly. 7000 grains = 1 pound.
Ballistics is one of the few modern contexts where grains are essential.
Some older pharmacology dosing survives in grain units — 5 gr ≈ 325 mg.

Avoid these

Confusing the grain (mass) with the troy grain in older precious-metal contexts — they are identical (64.8 mg).
Assuming "grain" refers to an amount of cereal — in firearms it is always a weight.
Reading "5 gr" as 5 grams — it is 5 grains (324 mg).

Frequently asked questions

How many carats in a grain?

One grain equals 0.324 carats.

How do I convert grains to carats?

Multiply the grain value by 0.324 to get the equivalent in carats.

What is 100 grains in carats?

100 grains equals 32.3995 carats.

Is a grain bigger than a carat?

No. 1 grain equals 0.324 carats, so one grain is smaller.

How to convert grains to carats without a calculator?

Multiply by 0.32 for a quick estimate; use a calculator for precise results.

Related weight conversions

📊 See full comparison matrix →

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