Mass and Weight · Unit Converter

Convert Carat (metric) to Gigagram

Convert carats (metric) to gigagrams instantly. 1 carat (metric) = 2e-10 gigagram — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Gigagram 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

Gigagram

What is a gigagram?

A gigagram (Gg) equals 10^6 kilograms, the same as 1,000 metric tons.

Origin of the gigagram

From the SI prefix 'giga-' (from Greek 'gigas', giant).

Where it is used

Bulk commodity, emissions, and freight accounting.

When and where it was developed

The giga- prefix entered the SI in 1960.

Carat (metric) to Gigagram conversion formula

The relationship between carats (metric) and gigagrams:

1 ct = 2e-10 Gg

1 Gg = 5e+9 ct

To convert carats (metric) to gigagrams, multiply the value in carats (metric) by 2e-10. To reverse, multiply gigagrams by 5e+9.

How to use this converter

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

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

Write down the value in carats (metric) (ct).
Multiply that value by the factor 2e-10.
The product is the equivalent value in gigagrams (Gg).
To reverse, multiply the gigagram value by 5e+9.

Worked examples

Example 1 — Convert 1 ct to Gg:
1 × 2e-10 = 2e-10 Gg

Example 2 — Convert 100 ct to Gg:
100 × 2e-10 = 2e-8 Gg

Real-world example — Plastic-film thickness alternates

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

150 ct × 2e-10 = 3e-8 Gg

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 gigagrams for direct comparison across supplier datasheets.

70 ct × 2e-10 = 1.4e-8 Gg

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 × 2e-10 = 6e-10 Gg

Carat (metric) to Gigagram conversion table

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

Carat (metric) [ct]	Gigagram [Gg]
0.01	2e-12
0.1	2e-11
1	2e-10
2	4e-10
3	6e-10
4	8e-10
5	1e-9
10	2e-9
20	4e-9
30	6e-9
40	8e-9
50	1e-8
100	2e-8
500	1e-7
1000	2e-7

Frequently asked questions

How many gigagrams is 1 carat (metric)?

1 carat (metric) equals 2e-10 gigagram.

How do I convert carats (metric) to gigagrams?

Multiply the value in carats (metric) by 2e-10 to get gigagrams.

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

Multiply the value in gigagrams by 5e+9, or use the Gigagram to Carat (metric) converter.

How many gigagrams is 100 carats (metric)?

100 carats (metric) equals 2e-8 gigagrams, because 100 × 2e-10 = 2e-8.

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 = 2e-10 Gg) 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.