How many carats is 1 gram?

Exactly 5 carats. Because 1 carat = 0.2 grams, dividing 1 gram by 0.2 gives 5 carats.

What is a metric carat?

A metric carat is a unit of mass equal to exactly 200 milligrams (0.2 grams), used internationally for weighing gemstones and pearls since 1907.

Is the jewelry carat the same as the gold karat?

No. The gemstone carat (ct) measures mass (1 ct = 0.2 g). The gold karat (k) measures purity (24k = pure gold). They are completely different units.

How precise is this converter?

The conversion factor is exact: 1 g = 5 ct. Results are displayed to up to 4 decimal places, matching the precision of professional gem scales.

Can I convert milligrams to carats?

Yes — divide your milligram value by 1000 to get grams, then enter that into this tool. For example, 500 mg = 0.5 g = 2.5 ct.

Grams to Carats Converter

Instantly convert grams to carats — enter any gram value and get the exact carat weight used in gemstone and jewelry measurement.

Grams to Carats

Mass in Grams (g)

Result in Carats (ct)

—

Formula: carats = grams ÷ 0.2

Carats to Grams (Reverse)

Mass in Carats (ct)

Result in Grams (g)

—

Formula: grams = carats × 0.2

Quick Reference — Common Conversions

Grams (g)	Carats (ct)	Common Context
0.2	1.0	1 carat — definition
0.4	2.0	Small diamond
1.0	5.0	1 gram = 5 carats
2.0	10.0	Medium sapphire rough
5.0	25.0	Large gemstone piece
10.0	50.0	Heavy rough stone
100.0	500.0	100 g parcel

Copied!

Summary

The carat (ct) is the standard unit of mass used worldwide to weigh diamonds, gemstones, and pearls. One metric carat equals exactly 0.2 grams, a definition established by the International Bureau of Weights and Measures. This tool converts any gram value to carats instantly, with full precision and a reverse carats-to-grams lookup.

How it works

Enter a mass value in grams in the input field.
The tool divides your value by 0.2 to calculate carats.
The result updates instantly as you type.
Use the reverse field to convert carats back to grams.
Copy either result with one click.

Use cases

Convert gem rough weight from grams to carats before pricing.
Verify gemstone weights quoted by a jeweler or lab report.
Calculate multi-stone carat totals from combined gram weights.
Convert between grams and carats when working with pearls.
Check diamond weight before and after cutting.
Quickly sanity-check carat figures on customs or import forms.
Teach students the gram-to-carat relationship in mineralogy.
Convert milligrams or kilograms to carats via the gram step.

Frequently Asked Questions

Last updated: 2026-10-05 · Reviewed by Nham Vu