Carats to Long Tons Converter

How to Convert Carats to Long Tons

To convert a weight measurement from carats to long tons, divide the weight by the conversion factor. Since one carat is equal to 1.9684 × 10^-7 long tons, you can use this formula:

The weight in long tons is equal to the carats divided by 5.0802 × 10⁶.

How Many Long Tons Are in a Carat?

There are 1.9684 × 10^-7 long tons in one carat.

What Is a Carat?

The carat (symbol: ct) is a unit of mass used for measuring gemstones and pearls, defined as exactly 200 milligrams (0.2 grams). The metric carat was adopted internationally in 1907 and is now the standard in the global gemstone and jewellery trade. The carat should not be confused with the karat (symbol: K or kt), which is a measure of the purity of gold alloys (24 karat = pure gold). The two terms share an etymological origin (from the Greek keration, meaning carob seed) but measure entirely different things. Carats are used universally in the diamond and gemstone industry. A 1-carat diamond weighs exactly 0.2 g and is approximately 6.5 mm in diameter for a round brilliant cut. Famous diamonds include the Hope Diamond (45.52 ct), the Cullinan I (530.2 ct), and the Koh-i-Noor (105.6 ct). In everyday jewellery, engagement ring diamonds in the US average about 1.0–1.5 carats. Diamond prices increase exponentially with carat weight: a 2-carat diamond typically costs more than double the price of a 1-carat diamond of the same quality, because larger stones are rarer.

One carat is equal to:

• 0.2 grams (g)
• 200 milligrams (mg)
• 0.0002 kilograms (kg)
• 0.007055 ounces (oz)
• 0.000441 pounds (lb)
• 2 × 10⁻⁷ metric tons (MT)

What Is a Long Ton?

The long ton (also called the imperial ton or displacement ton) is an imperial unit of weight equal to exactly 2,240 pounds (1,016.0469088 kilograms). It was the traditional ton used in the United Kingdom before metrication. The long ton is approximately 12% heavier than the US short ton (2,000 lb) and approximately 1.6% heavier than the metric ton (2,204.62 lb). These differences are important in international shipping and trade to avoid confusion and financial discrepancies. The long ton is still used in some specific contexts: the displacement of warships and large vessels is sometimes quoted in long tons (particularly in historical and naval contexts). In the UK, the long ton was the standard “ton” before the adoption of the metric ton. The long ton contains exactly 160 stones (160 × 14 = 2,240 lb) or 20 hundredweight (20 × 112 = 2,240 lb). The hundredweight (cwt) of 112 pounds is the traditional British hundredweight, distinct from the US hundredweight of 100 pounds.

One long ton is equal to:

• 2,240 pounds (lb)
• 35,840 ounces (oz)
• 1,016.047 kilograms (kg)
• 1,016,047 grams (g)
• 1.016047 metric tons (MT)
• 1.12 tons (t)
• 160 stones (st)
• 5,080,235 carats (ct)

Understanding Weight and Mass Units

Weight and mass are related but distinct concepts. Mass is the amount of matter in an object and is constant regardless of location. Weight is the force of gravity acting on that mass and varies with gravitational field strength. In everyday language, “weight” and “mass” are used interchangeably, and the units on this page measure mass.

Weight and mass units have evolved from different historical measurement systems, resulting in a rich variety of units still in use today.

Major Unit Systems

• Metric / SI units: The kilogram (kg) is the SI base unit of mass. Grams (g) and milligrams (mg) are derived using standard prefixes. The metric ton (tonne, 1,000 kg) is used for large masses.
• US customary / Imperial units: The pound (lb) is the primary unit, with 16 ounces per pound. The US short ton (2,000 lb) and the imperial long ton (2,240 lb) are used for large masses. The stone (14 lb) is used in the UK for body weight.
• Specialised units: The carat (0.2 g) is used for gemstones. The Calorie (kcal) is used as a proxy for weight change based on the 3,500 kcal per pound approximation.

Key Conversion Relationships

• 1 pound (lb) = 453.59237 grams (exact by international agreement)
• 1 kilogram (kg) = 2.204623 pounds
• 1 ounce (oz) = 28.349523 grams = 1/16 pound
• 1 stone (st) = 14 pounds = 6.350293 kg
• 1 US ton (t) = 2,000 pounds = 907.185 kg
• 1 long ton (lt) = 2,240 pounds = 1,016.047 kg
• 1 metric ton (MT) = 1,000 kg = 2,204.623 pounds
• 1 carat (ct) = 0.2 grams = 200 milligrams (exact)

Tips for Weight Conversions

• The most important conversion to remember: 1 kg ≈ 2.2 lb. Multiply kilograms by 2.2 for a quick pounds estimate, or divide pounds by 2.2 for kilograms.
• For ounces to grams: 1 oz ≈ 28.35 g. Multiply ounces by 28 for a rough gram estimate.
• UK body weight in stones: divide pounds by 14. For example, 154 lb = 11 stone.
• Don’t confuse the three types of “ton”: US short ton = 2,000 lb, metric ton = 2,204.6 lb, long (imperial) ton = 2,240 lb.
• The metric ton is about 10% heavier than the US short ton. When reading international commodity prices, check which ton is being used.
• For gemstones: 1 carat = 0.2 grams exactly, so 5 carats = 1 gram. A 1-carat diamond is about the size of a pencil eraser top.
• Don’t confuse avoirdupois ounces (28.35 g, for general weighing) with troy ounces (31.10 g, for precious metals) or fluid ounces (a volume measure).
• The Calorie-to-weight conversion (3,500 kcal per pound) is a nutritional approximation, not a physical constant. It is useful for rough weight-loss estimates but not for precise calculations.

Carats to Long Tons Conversion Table

The following table shows conversions from carats to long tons.

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