Mass and Weight · Unit Converter

Convert Carat (metric) to Pound (troy/apothecary)

Convert carats (metric) to pounds (troy/apothecary) instantly. 1 carat (metric) = 0.0005358458 pound (troy/apothecary) — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Pound (troy/apothecary) 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.

Troy & Apothecary

Pound (troy/apothecary)

What is a pound (troy/apothecary)?

The troy (apothecary) pound equals 12 troy ounces, about 373.24 grams.

Origin of the pound (troy/apothecary)

Named for Troyes, France, a major medieval trade-fair town.

Where it is used

Historical pricing of precious metals; now largely superseded by the troy ounce.

When and where it was developed

Adopted as the English coinage standard under Henry VIII in 1528.

Carat (metric) to Pound (troy/apothecary) conversion formula

The relationship between carats (metric) and pounds (troy/apothecary):

1 ct = 0.0005358458 lb t

1 lb t = 1866.208608 ct

To convert carats (metric) to pounds (troy/apothecary), multiply the value in carats (metric) by 0.0005358458. To reverse, multiply pounds (troy/apothecary) by 1866.208608.

How to use this converter

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

Step-by-step: convert carats (metric) to pounds (troy/apothecary)

Write down the value in carats (metric) (ct).
Multiply that value by the factor 0.0005358458.
The product is the equivalent value in pounds (troy/apothecary) (lb t).
To reverse, multiply the pound (troy/apothecary) value by 1866.208608.

Worked examples

Example 1 — Convert 1 ct to lb t:
1 × 0.0005358458 = 0.0005358458 lb t

Example 2 — Convert 100 ct to lb t:
100 × 0.0005358458 = 0.0535845776 lb t

Real-world example — Quarter-meter measurement reference

A 250,000-carat (metric) length equals 0.25 pounds (troy/apothecary) — useful for comparing supply-chain spec sheets where some lengths are quoted in the smaller unit and some in the larger.

250000 ct × 0.0005358458 = 133.9614440359 lb t

Real-world example — From microscopic to macroscopic

A million carats (metric) equals exactly one pound (troy/apothecary). This kind of conversion appears in microfluidics, where total channel length is given in pounds (troy/apothecary) but feature widths are in carats (metric).

1000000 ct × 0.0005358458 = 535.8457761438 lb t

Real-world example — Macro-scale buildup

A million carats (metric) equals exactly one pound (troy/apothecary) — the conversion that bridges microscale features and macroscale objects in microfluidic, biomedical, and semiconductor packaging design.

1000000 ct × 0.0005358458 = 535.8457761438 lb t

Carat (metric) to Pound (troy/apothecary) conversion table

Standard reference values for converting carats (metric) to pounds (troy/apothecary):

Carat (metric) [ct]	Pound (troy/apothecary) [lb t]
0.01	5.358458e-6
0.1	5.358458e-5
1	0.0005358458
2	0.0010716916
3	0.0016075373
4	0.0021433831
5	0.0026792289
10	0.0053584578
20	0.0107169155
30	0.0160753733
40	0.021433831
50	0.0267922888
100	0.0535845776
500	0.2679228881
1000	0.5358457761

Frequently asked questions

How many pounds (troy/apothecary) is 1 carat (metric)?

1 carat (metric) equals 0.0005358458 pound (troy/apothecary).

How do I convert carats (metric) to pounds (troy/apothecary)?

Multiply the value in carats (metric) by 0.0005358458 to get pounds (troy/apothecary).

How do I convert pounds (troy/apothecary) back to carats (metric)?

Multiply the value in pounds (troy/apothecary) by 1866.208608, or use the Pound (troy/apothecary) to Carat (metric) converter.

How many pounds (troy/apothecary) is 100 carats (metric)?

100 carats (metric) equals 0.0535845776 pounds (troy/apothecary), because 100 × 0.0005358458 = 0.0535845776.

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 = 0.0005358458 lb t) 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.