Convert carats to grains

1 ct=3.08647gr

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

You have

Equals

3.086472

Conversion formula

Forward

grains = carats × 3.08647

Reverse

carats = grains × 0.324

Example: 10 ct × 3.08647 = 30.8647 gr.

About both units

From

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

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 to Grain conversion table

Common carats to grains values for quick reference.

Carat (ct)	Grain (gr)
1 ct	3.08647 gr
5 ct	15.4324 gr
10 ct	30.8647 gr
25 ct	77.1618 gr
50 ct	154.324 gr
100 ct	308.647 gr
250 ct	771.618 gr
500 ct	1,543.24 gr
1,000 ct	3,086.47 gr
5,000 ct	15,432.36 gr

Tips & common mistakes

Quick tips

1 carat = 200 mg = 0.2 g exactly since 1907.
Carat (gem weight) and karat (gold purity, 24 K = pure) are different words with different meanings.
A carat is divided into 100 points; a 0.25 ct diamond is called a "25-pointer".

Avoid these

Confusing carat (mass) with karat (gold purity).
Assuming a 2-carat diamond is twice the physical size of a 1-carat — volume scales with cube root of mass.
Using "karat" on gemstone certificates — international standard is "carat" spelled with a C.

Frequently asked questions

How many grains in a carat?

One carat equals 3.08647 grains.

How do I convert carats to grains?

Multiply the carat value by 3.08647 to get the equivalent in grains.

What is 100 carats in grains?

100 carats equals 308.647 grains.

Is a carat bigger than a grain?

Yes. 1 carat equals 3.08647 grains, so one carat is larger.

How to convert carats to grains without a calculator?

Multiply by 3.09 for a quick estimate; use a calculator for precise results.

Related weight conversions

📊 See full comparison matrix →

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