Mass and Weight · Unit Converter

Convert Carat (metric) to Milligram

Convert carats (metric) to milligrams instantly. 1 carat (metric) = 200 milligram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Milligram to Carat (metric) converter for the reverse conversion.

Written by Sunith Babu L, Ph.D., Lead Engineer Reviewed by Dr. Ashok Kumar K, Ph.D.

Mass and Weight category 2 min read Published June 10, 2026 Last reviewed June 10, 2026 Updated June 10, 2026

Units explained

Troy & Apothecary

Carat (metric)

What is a carat (metric)?

The metric carat (ct) equals exactly 200 milligrams (0.0002 kg).

Origin of the carat (metric)

From Arabic 'qirat' and Greek 'keration', the carob seed once used as a counterweight.

Where it is used

The worldwide standard for gemstone and diamond mass.

When and where it was developed

The metric carat was fixed at 200 mg internationally in 1907.

Metric / SI

Milligram

What is a milligram?

A milligram (mg) equals one-millionth of a kilogram, or 0.001 gram.

Origin of the milligram

From the SI prefix 'milli-' (from Latin 'mille', thousand).

Where it is used

Standard for medicine dosing, nutrition labels, and fine jewelry.

When and where it was developed

Part of the original metric system of 1795.

Carat (metric) to Milligram conversion formula

The relationship between carats (metric) and milligrams:

1 ct = 200 mg

1 mg = 0.005 ct

To convert carats (metric) to milligrams, multiply the value in carats (metric) by 200. To reverse, multiply milligrams by 0.005.

How to use this converter

Type a value into the calculator. The result in milligrams updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Milligram to Carat (metric) converter for the reverse direction.

Step-by-step: convert carats (metric) to milligrams

Write down the value in carats (metric) (ct).
Multiply that value by the factor 200.
The product is the equivalent value in milligrams (mg).
To reverse, multiply the milligram value by 0.005.

Worked examples

Example 1 — Convert 1 ct to mg:
1 × 200 = 200 mg

Example 2 — Convert 100 ct to mg:
100 × 200 = 20000 mg

Real-world example — Paper and film thicknesses

At the thickness of office paper (roughly 3 carats (metric)), converting between sub-millimeter units is routine for packaging and printing buyers comparing quotes from metric and US suppliers.

3 ct × 200 = 600 mg

Real-world example — Plastic-film thickness alternates

A 150-carat (metric) plastic film converts cleanly to milligrams — useful for packaging buyers reconciling supplier datasheets across metric and US measurement systems.

150 ct × 200 = 30000 mg

Real-world example — Hair-width scale measurements

A 70-carat (metric) measurement (about the diameter of a human hair) is the kind of value materials engineers regularly express in adjacent micro-scale units like milligrams for direct comparison across supplier datasheets.

70 ct × 200 = 14000 mg

Carat (metric) to Milligram conversion table

Standard reference values for converting carats (metric) to milligrams:

Carat (metric) [ct]	Milligram [mg]
0.01	2
0.1	20
1	200
2	400
3	600
4	800
5	1000
10	2000
20	4000
30	6000
40	8000
50	10000
100	20000
500	100000
1000	200000

Frequently asked questions

How many milligrams is 1 carat (metric)?

1 carat (metric) equals 200 milligram.

How do I convert carats (metric) to milligrams?

Multiply the value in carats (metric) by 200 to get milligrams.

How do I convert milligrams back to carats (metric)?

Multiply the value in milligrams by 0.005, or use the Milligram to Carat (metric) converter.

How many milligrams is 100 carats (metric)?

100 carats (metric) equals 20000 milligrams, because 100 × 200 = 20000.

Convert Carat (metric) to other weight units

Show all Carat (metric) conversions

Metric / SI (18 units)

Avoirdupois (15 units)

Troy & Apothecary (9 units)

Carat (metric) to Point (1/100 carat) (pt) Carat (metric) to Scruple (apothecary) (s ap) Carat (metric) to Pennyweight (dwt) Carat (metric) to Momme (mom) Carat (metric) to Mace (mace) Carat (metric) to Dram (apothecary/troy) (dr ap) Carat (metric) to Troy Ounce (oz t) Carat (metric) to Tael (tael) Carat (metric) to Pound (troy/apothecary) (lb t)

Indian / South Asian (6 units)

Carat (metric) to Ratti (ratti) Carat (metric) to Masha (masha) Carat (metric) to Tola (tola) Carat (metric) to Chittack (Chatank) (chittack) Carat (metric) to Seer (Ser) (seer) Carat (metric) to Maund (Mann) (maund)

Scientific / Atomic (9 units)

Carat (metric) to Electron Mass (rest) (me) Carat (metric) to MeV/c2 (MeV/c²) Carat (metric) to Muon Mass (mµ) Carat (metric) to Atomic Mass Unit (u) Carat (metric) to Proton Mass (mp) Carat (metric) to Neutron Mass (mn) Carat (metric) to Deuteron Mass (md) Carat (metric) to Carbon-12 Atom Mass (C-12) Carat (metric) to Planck Mass (mP)

Astronomical (4 units)

Carat (metric) to Lunar Mass (Moon) (M☾) Carat (metric) to Earth's Mass (M⊕) Carat (metric) to Jupiter Mass (MJ) Carat (metric) to Sun's Mass (M☉)

Biblical / Ancient (14 units)

Carat (metric) to Lepton (Biblical Roman) (lepton) Carat (metric) to Quadrans (Biblical Roman) (quadrans) Carat (metric) to Assarion (Biblical Roman) (assarion) Carat (metric) to Gerah (Biblical Hebrew) (gerah) Carat (metric) to Drachma (Biblical Greek) (drachma) Carat (metric) to Denarius (Biblical Roman) (denarius) Carat (metric) to Bekan (Biblical Hebrew) (bekah) Carat (metric) to Didrachma (Biblical Greek) (didrachma) Carat (metric) to Shekel (Biblical Hebrew) (shekel) Carat (metric) to Tetradrachma (Biblical Greek) (tetra) Carat (metric) to Mina (Biblical Greek) (mina) Carat (metric) to Mina (Biblical Hebrew) (mina) Carat (metric) to Talent (Biblical Greek) (talent) Carat (metric) to Talent (Biblical Hebrew) (talent)

Force / Engineering (5 units)

Carat (metric) to Poundal (pdl) Carat (metric) to Ton (assay) (US) (AT) Carat (metric) to Ton (assay) (UK) (AT) Carat (metric) to Kilogram-force square second/meter (hyl) Carat (metric) to Slug (slug)

Sources & references

Conversion factor (1 ct = 200 mg) verified against the following authoritative sources:

BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.

Results are provided for general reference. Verify critical measurements against an authoritative standard.