Mass and Weight · Unit Converter

Convert Carat (metric) to Atomic Mass Unit

Convert carats (metric) to atomic mass unit instantly. 1 carat (metric) = 1.204427e+23 atomic mass unit — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Atomic Mass Unit 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

Atomic Mass Unit

What is a atomic mass unit?

One unified atomic mass unit (u) is defined as 1/12 the mass of a carbon-12 atom, about 1.6605E-27 kg.

Origin of the atomic mass unit

Introduced to give atomic and molecular masses convenient numerical values.

Where it is used

Atomic, molecular, and nuclear physics and chemistry.

When and where it was developed

The unified (carbon-12) scale was adopted by IUPAC and IUPAP in 1960-1961.

Carat (metric) to Atomic Mass Unit conversion formula

The relationship between carats (metric) and atomic mass unit:

1 ct = 1.204427e+23 u

1 u = 8.302701e-24 ct

To convert carats (metric) to atomic mass unit, multiply the value in carats (metric) by 1.204427e+23. To reverse, multiply atomic mass unit by 8.302701e-24.

How to use this converter

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

Step-by-step: convert carats (metric) to atomic mass unit

Write down the value in carats (metric) (ct).
Multiply that value by the factor 1.204427e+23.
The product is the equivalent value in atomic mass unit (u).
To reverse, multiply the atomic mass unit value by 8.302701e-24.

Worked examples

Example 1 — Convert 1 ct to u:
1 × 1.204427e+23 = 1.204427e+23 u

Example 2 — Convert 100 ct to u:
100 × 1.204427e+23 = 1.204427e+25 u

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

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

1 ct × 1.204427e+23 = 1.204427e+23 u

Real-world example — Infrared to visible-spectrum mapping

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

10 ct × 1.204427e+23 = 1.204427e+24 u

Real-world example — Mid-micron to nanometer

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

3 ct × 1.204427e+23 = 3.613282e+23 u

Carat (metric) to Atomic Mass Unit conversion table

Standard reference values for converting carats (metric) to atomic mass unit:

Carat (metric) [ct]	Atomic Mass Unit [u]
0.01	1.204427e+21
0.1	1.204427e+22
1	1.204427e+23
2	2.408855e+23
3	3.613282e+23
4	4.817709e+23
5	6.022137e+23
10	1.204427e+24
20	2.408855e+24
30	3.613282e+24
40	4.817709e+24
50	6.022137e+24
100	1.204427e+25
500	6.022137e+25
1000	1.204427e+26

Frequently asked questions

How many atomic mass unit is 1 carat (metric)?

1 carat (metric) equals 1.204427e+23 atomic mass unit.

How do I convert carats (metric) to atomic mass unit?

Multiply the value in carats (metric) by 1.204427e+23 to get atomic mass unit.

How do I convert atomic mass unit back to carats (metric)?

Multiply the value in atomic mass unit by 8.302701e-24, or use the Atomic Mass Unit to Carat (metric) converter.

How many atomic mass unit is 100 carats (metric)?

100 carats (metric) equals 1.204427e+25 atomic mass unit, because 100 × 1.204427e+23 = 1.204427e+25.

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 = 1.204427e+23 u) 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.