Mass and Weight · Unit Converter

Convert Carat (metric) to Ton (long, UK)

Convert carats (metric) to tons (long, uk) instantly. 1 carat (metric) = 1.968413e-7 ton (long, uk) — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Ton (long, UK) 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.

Avoirdupois

Ton (long, UK)

What is a ton (long, uk)?

The long (UK) ton equals 2,240 pounds, about 1,016 kilograms.

Origin of the ton (long, uk)

The British imperial ton, equal to 20 long hundredweight.

Where it is used

UK shipping and historical heavy industry.

When and where it was developed

Standardized within the British imperial system.

Carat (metric) to Ton (long, UK) conversion formula

The relationship between carats (metric) and tons (long, uk):

1 ct = 1.968413e-7 long tn

1 long tn = 5080234.5439999998 ct

To convert carats (metric) to tons (long, uk), multiply the value in carats (metric) by 1.968413e-7. To reverse, multiply tons (long, uk) by 5080234.5439999998.

How to use this converter

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

Step-by-step: convert carats (metric) to tons (long, uk)

Write down the value in carats (metric) (ct).
Multiply that value by the factor 1.968413e-7.
The product is the equivalent value in tons (long, uk) (long tn).
To reverse, multiply the ton (long, uk) value by 5080234.5439999998.

Worked examples

Example 1 — Convert 1 ct to long tn:
1 × 1.968413e-7 = 1.968413e-7 long tn

Example 2 — Convert 100 ct to long tn:
100 × 1.968413e-7 = 1.968413e-5 long tn

Real-world example — Feature-scale to long-haul

One billion carats (metric) equals exactly one ton (long, uk) — the conversion an optical-network engineer performs when totalling feature-level path lengths into a single long-haul fiber-link distance.

1e+9 ct × 1.968413e-7 = 196.8413055222 long tn

Real-world example — Fiber-optic link lengths

Converting from microscale carats (metric) to the tons (long, uk) of a long-haul fiber link is the conversion an optical engineer performs when calculating attenuation per kilometre of fiber.

1e+9 ct × 1.968413e-7 = 196.8413055222 long tn

Carat (metric) to Ton (long, UK) conversion table

Standard reference values for converting carats (metric) to tons (long, uk):

Carat (metric) [ct]	Ton (long, UK) [long tn]
0.01	1.968413e-9
0.1	1.968413e-8
1	1.968413e-7
2	3.936826e-7
3	5.905239e-7
4	7.873652e-7
5	9.842065e-7
10	1.968413e-6
20	3.936826e-6
30	5.905239e-6
40	7.873652e-6
50	9.842065e-6
100	1.968413e-5
500	9.842065e-5
1000	0.0001968413

Frequently asked questions

How many tons (long, uk) is 1 carat (metric)?

1 carat (metric) equals 1.968413e-7 ton (long, uk).

How do I convert carats (metric) to tons (long, uk)?

Multiply the value in carats (metric) by 1.968413e-7 to get tons (long, uk).

How do I convert tons (long, uk) back to carats (metric)?

Multiply the value in tons (long, uk) by 5080234.5439999998, or use the Ton (long, UK) to Carat (metric) converter.

How many tons (long, uk) is 100 carats (metric)?

100 carats (metric) equals 1.968413e-5 tons (long, uk), because 100 × 1.968413e-7 = 1.968413e-5.

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 = 1.968413e-7 long tn) 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.