Carats to Milligrams Converter

Multiply carats by 200 to get milligrams. 1 carat = 200 mg exactly. For example, 0.5 ct = 100 mg and 2 ct = 400 mg.

Carats

Milligrams

Common Conversions

Key Takeaways

1 carat = 200 milligrams exactly. Multiply carats by 200.
0.01 carats (1 point) = 2 milligrams.
5 carats = 1,000 milligrams = 1 gram.
Gemological scales measure to 0.2 mg (0.001 carats).
The 200 mg definition has been standard since 1907.

How Do You Convert Carats to Milligrams?

Multiply carats by 200 to get milligrams. The formula is: Milligrams = Carats x 200. The metric carat is defined as exactly 200 milligrams, making this conversion exact with no rounding needed.

Leah Novak weighs vanilla extract for a precision pastry recipe. She needs exactly 0.25 carats of saffron threads (measured on a jeweler scale she borrowed). Converting: 0.25 x 200 = 50 milligrams of saffron. Her kitchen scale cannot measure this precisely, so the jeweler scale (accurate to 0.2 mg) gives her the exact amount needed.

Precision Weight Reference

Carats	Milligrams	Reference
0.01 ct (1 point)	2 mg	Smallest commercial diamond
0.05 ct (5 points)	10 mg	Melee diamond
0.1 ct	20 mg	Small accent stone
0.25 ct	50 mg	Quarter carat solitaire
0.5 ct	100 mg	Half carat engagement ring
1.0 ct	200 mg	Classic one-carat diamond
2.0 ct	400 mg	Large engagement diamond
5.0 ct	1,000 mg	Exceptional collector stone

Practical Applications

Gemstone Certification

Sam Okafor sends a diamond for GIA certification. The lab weighs it at 1.037 carats = 207.4 milligrams. The certificate rounds to 1.03 carats. He explains to his client that the stone is officially 1.03 ct, not 1.04, because GIA always rounds down. The 1.4 mg difference (7 ten-thousandths of a carat) is invisible but affects the certificate grade.

Pharmaceutical Comparison

Maya Singh compares measurement scales in a chemistry class. A standard aspirin tablet is 325 mg = 1.625 carats. A typical engagement diamond at 0.7 carats = 140 mg weighs less than half an aspirin tablet. She finds it remarkable that such a tiny amount of carbon (140 mg) can be worth thousands of dollars.

Quality Control

Dana Kowalski calibrates precision equipment at a gemstone processing facility. Calibration weights of 100, 200, and 500 mg (0.5, 1.0, and 2.5 carats) are used to verify each scale daily. The tolerance is plus or minus 0.4 mg (0.002 carats). She documents each calibration for the quality management system.

Frequently Asked Questions

How many milligrams is 1 carat?

One carat equals exactly 200 milligrams. This is the international standard adopted in 1907 by the General Conference on Weights and Measures.

How do I convert carats to milligrams?

Multiply carats by 200 to get milligrams. For example, 0.5 ct = 100 mg, 1.5 ct = 300 mg, and 2 ct = 400 mg.

What is a diamond point in milligrams?

One diamond point = 0.01 carats = 2 milligrams. A 50-point diamond weighs 100 mg (0.5 carats). Points provide precision for small stones.

Why use milligrams instead of carats?

Laboratories and scientific contexts prefer milligrams because they integrate with the metric system. Gemologists prefer carats because the trade has used them for centuries and the numbers are more convenient.

How precise are gemstone weight measurements?

Professional gemological scales measure to 0.001 carats (0.2 mg). High-end lab balances can resolve 0.01 mg (0.00005 carats). Certificates typically round to 0.01 carats (2 mg).