Convert Carat to US Ton (ct → ton (US))

Converting carats to US tons is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in carats

   Start with the number of carats (ct) you want to convert.
2. 2
   Multiply by 2.205e-7

   The conversion factor from ct to ton (US) is 2.205e-7. Multiply your value by this number.
3. 3
   Read the result in US tons

   The result is your value in US tons (ton (US)).

Multiply the value in carats by 2.205e-7. For the reverse direction, multiply by 4,535,923.7.

• ✓1 carat = 200 mg = 0.2 g exactly since 1907.
• ✓Carat (gem weight) and karat (gold purity, 24 K = pure) are different words with different meanings.
• ✓A carat is divided into 100 points; a 0.25 ct diamond is called a "25-pointer".

• ✗Confusing carat (mass) with karat (gold purity).
• ✗Assuming a 2-carat diamond is twice the physical size of a 1-carat — volume scales with cube root of mass.
• ✗Using "karat" on gemstone certificates — international standard is "carat" spelled with a C.

What is the Carat?

The carat equals exactly 200 milligrams (0.2 g) and is the universal unit for gemstone and diamond weight in the global jewelry industry. The word derives from the Greek 'keration' and the Arabic 'qīrāṭ,' both referring to carob seeds, which were once used as natural counterweights for weighing gems because they have remarkably uniform mass. The metric carat was standardized in 1907 at exactly 200 mg, replacing dozens of regional carat values that had varied between 188 and 213 mg. A 1-carat diamond is roughly 6.5 mm in diameter, and the famous Hope Diamond weighs 45.52 carats. The carat is distinct from the karat (with a 'k'), which measures gold purity (24-karat = 100% gold). It relates to the gram (5 ct = 1 g) and the milligram (200 mg = 1 ct). Gem dealers commonly use 'points' for fractions (100 points = 1 carat).

• Diamond and gemstone retail and valuation
• Jewellery manufacturing and design
• International gem certification (GIA, IGI)

What is the US Ton?

The US short ton equals exactly 2,000 pounds or 907.18474 kilograms, and is the standard weight unit for American freight, mining, construction, and waste management. Its name distinguishes it from the longer UK long ton (2,240 lb). The short ton emerged in the United States during the 19th century to simplify calculations: 2,000 is a rounder number than 2,240. Today it dominates American industry — coal mining quotes production in short tons, dump trucks are rated by short-ton capacity, and the EPA tracks emissions in short tons. Imperial-to-metric confusion can be costly: in 1999, the Mars Climate Orbiter spacecraft was lost partly due to a units mismatch involving pounds and newtons. The short ton relates to the pound (2,000 lb = 1 ton), the metric ton (1 short ton ≈ 0.907 t), and the long ton (1 long ton = 1.12 short tons).

• US freight and trucking weight limits
• US coal and mining production
• US shipbuilding and heavy industry