How many carats are in one grain?

One grain (gr) equals exactly 0.32399455 carats (ct). This is derived from the fact that 1 grain = 64.79891 milligrams and 1 carat = 200 milligrams, so the factor is 64.79891 / 200 = 0.32399455.

Is a grain the same as a gram?

No. A grain is much smaller than a gram. One grain equals approximately 0.06479891 grams, while one gram equals roughly 15.432 grains.

What is a carat used to measure?

A metric carat (ct) is the standard unit for measuring the weight of gemstones and pearls. One carat equals exactly 200 milligrams (0.2 grams). It is different from karat (kt), which measures gold purity.

Where is the grain unit still used today?

Grains are still widely used in the United States for measuring gunpowder and bullet weights in ammunition (e.g., a 55-grain bullet), as well as in traditional pharmacy and archery arrow weights.

Can I convert carats back to grains with this tool?

Yes. Click the swap button to reverse the conversion direction. Entering a value in carats will then show the equivalent in grains.

How precise is the conversion?

The tool uses the exact factor 1 grain = 0.32399455 carats, which derives from the internationally defined grain of 64.79891 mg and the metric carat of 200 mg. Results are displayed to 6 decimal places.

Grains to Carats Converter

Name: Grains to Carats Converter
Availability: InStock
Author: Nham Vu

Enter a weight in grains and instantly get the equivalent in carats using the exact conversion factor.

Enter Weight

Grains (gr)

Carats (ct)

Result

Enter a value to see the result

Exact factor: 1 grain = 0.32399455 ct | 1 ct = 3.08647 gr

Quick Reference Table

Common grain values converted to carats

Grains (gr)	Carats (ct)	Milligrams (mg)

Summary

Enter a weight in grains and instantly get the equivalent in carats using the exact conversion factor.

How it works

Enter a weight value in the grains input field.
The converter applies the exact factor: 1 grain = 0.32399455 carats.
The result in carats appears instantly as you type.
Use the swap button to convert carats back to grains.
Copy the result with one click for use elsewhere.

Use cases

Convert bullet or powder weights from grains to carats for gemological comparisons.
Cross-reference traditional pharmacy grain measurements with carat-based scales.
Convert historical precious metal weights recorded in grains to modern carat values.
Verify scale readings when switching between grain and carat measurement modes.
Educational reference for students learning unit conversion in physics or chemistry.
Jewelers verifying weights across different measurement systems.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu