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

Converting carats to UK 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 1.968e-7

   The conversion factor from ct to ton (UK) is 1.968e-7. Multiply your value by this number.
3. 3
   Read the result in UK tons

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

Multiply the value in carats by 1.968e-7. For the reverse direction, multiply by 5,080,234.5.

• ✓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 UK Ton?

The UK long ton equals exactly 2,240 pounds or 1,016.0469088 kilograms, and was historically the standard weight unit in the British Empire and remains in use in shipping, mining, and engineering throughout the United Kingdom and Commonwealth countries. The long ton is closer in size to the metric ton (only 1.6% lighter), which is why it has resisted complete replacement. Shipping displacement, especially of older and military vessels, is often quoted in long tons (the British Royal Navy historically used long tons for ship tonnage). It relates to the hundredweight (20 cwt = 1 long ton), the pound (2,240 lb = 1 long ton), and the metric ton (1 long ton ≈ 1.016 t). The long ton's name reflects its larger size compared to the US short ton (2,000 lb).

• Older UK shipping and commodity contracts
• British naval displacement tonnage (ships)
• Historical coal and steel production data