Mass and Weight · Unit Converter

Convert Carat (metric) to Carbon-12 Atom Mass

Convert carats (metric) to carbon-12 atom mass instantly. 1 carat (metric) = 1.00369e+22 carbon-12 atom mass — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Carbon-12 Atom Mass 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.

Scientific / Atomic

Carbon-12 Atom Mass

What is a carbon-12 atom mass?

The mass of a single carbon-12 atom is exactly 12 u by definition, about 1.9926E-26 kg.

Origin of the carbon-12 atom mass

The reference nuclide that defines the unified atomic mass scale.

Where it is used

The defining standard for the atomic mass unit.

When and where it was developed

Chosen as the mass standard by IUPAC and IUPAP in 1960-1961.

Carat (metric) to Carbon-12 Atom Mass conversion formula

The relationship between carats (metric) and carbon-12 atom mass:

1 ct = 1.00369e+22 C-12

1 C-12 = 9.963234e-23 ct

To convert carats (metric) to carbon-12 atom mass, multiply the value in carats (metric) by 1.00369e+22. To reverse, multiply carbon-12 atom mass by 9.963234e-23.

How to use this converter

Type a value into the calculator. The result in carbon-12 atom mass updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Carbon-12 Atom Mass to Carat (metric) converter for the reverse direction.

Step-by-step: convert carats (metric) to carbon-12 atom mass

Write down the value in carats (metric) (ct).
Multiply that value by the factor 1.00369e+22.
The product is the equivalent value in carbon-12 atom mass (C-12).
To reverse, multiply the carbon-12 atom mass value by 9.963234e-23.

Worked examples

Example 1 — Convert 1 ct to C-12:
1 × 1.00369e+22 = 1.00369e+22 C-12

Example 2 — Convert 100 ct to C-12:
100 × 1.00369e+22 = 1.00369e+24 C-12

Real-world example — Mid-micron to nanometer

3 carats (metric) equals 3,000 carbon-12 atom mass — useful when relating mid-infrared wavelengths (typically quoted in microns) to nanometer-scale visible-light wavelength tables.

3 ct × 1.00369e+22 = 3.01107e+22 C-12

Real-world example — From microns to sub-micron features

One carat (metric) equals one thousand carbon-12 atom mass — the conversion semiconductor designers do constantly when comparing mask feature dimensions to actual transistor gate lengths.

1 ct × 1.00369e+22 = 1.00369e+22 C-12

Real-world example — Infrared to visible-spectrum mapping

A 10-carat (metric) thermal infrared wavelength corresponds to a much larger number in carbon-12 atom mass, the unit favoured for ultraviolet and visible-light specifications.

10 ct × 1.00369e+22 = 1.00369e+23 C-12

Carat (metric) to Carbon-12 Atom Mass conversion table

Standard reference values for converting carats (metric) to carbon-12 atom mass:

Carat (metric) [ct]	Carbon-12 Atom Mass [C-12]
0.01	1.00369e+20
0.1	1.00369e+21
1	1.00369e+22
2	2.00738e+22
3	3.01107e+22
4	4.014761e+22
5	5.018451e+22
10	1.00369e+23
20	2.00738e+23
30	3.01107e+23
40	4.014761e+23
50	5.018451e+23
100	1.00369e+24
500	5.018451e+24
1000	1.00369e+25

Frequently asked questions

How many carbon-12 atom mass is 1 carat (metric)?

1 carat (metric) equals 1.00369e+22 carbon-12 atom mass.

How do I convert carats (metric) to carbon-12 atom mass?

Multiply the value in carats (metric) by 1.00369e+22 to get carbon-12 atom mass.

How do I convert carbon-12 atom mass back to carats (metric)?

Multiply the value in carbon-12 atom mass by 9.963234e-23, or use the Carbon-12 Atom Mass to Carat (metric) converter.

How many carbon-12 atom mass is 100 carats (metric)?

100 carats (metric) equals 1.00369e+24 carbon-12 atom mass, because 100 × 1.00369e+22 = 1.00369e+24.

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 = 1.00369e+22 C-12) 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 Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.

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