Convert tons to kilograms

A US short ton is 907.18474 kilograms[1] and a British long ton of 2,240 pounds[2] is 1,016.0469088 kilograms. Both numbers are exact, because both tons are defined in pounds and a pound is exactly 0.45359237 kilograms[1].

The metric tonne is a round number instead: exactly 1,000 kilograms[3]. That gives three multipliers for one word, and you choose which one the calculation uses with the Ton type selector under the fields.

Two short tons come to 1,814.37 kilograms and ten short tons to 9,071.85 kilograms. The same ten tons read as metric tonnes give a flat 10,000 kilograms, which is 928.15 kilograms more than the American reading of the same figure. For a quick estimate in your head, multiply by 907 for short tons and by 1,016 for long tons.

For the opposite direction, use the kilograms to tons converter, and for the same ton in pounds, the tons to pounds converter.

The metric tonne is a unit of mass equal to 1,000 kilograms, written with the symbol t. It is not an SI unit, but it is accepted for use with SI units[3]. In the United States the same unit carries the name metric ton[3].

Inside the SI the same mass is called a megagram, symbol Mg, but that name is rarely used, partly because the SI base unit of mass is the kilogram rather than the gram[4]. A megagram is a million grams, and that is the figure the tons to grams converter gives. Write the M as a capital, because mg is a milligram, a billion times smaller.

The kilogram is the SI base unit of mass. In November 2018 the international scientific community voted to redefine it in terms of the Planck constant, an invariant of nature[5]. Before that, the kilogram was a small polished cylinder of platinum and iridium, cast in 1879 and kept in a triple-locked vault on the outskirts of Paris[5].

There is one more unit between the two. In the United States the plain word hundredweight means 100 pounds, which is 45.36 kilograms, while the gross or long hundredweight is 112 pounds, which is 50.80 kilograms[6]. Twenty of either make a ton: 20 times 100 pounds is the 2,000-pound short ton, and 20 times 112 pounds is the 2,240-pound long ton[6].

Which ton you need depends on where the number came from. In the United States the word ton on its own means the 2,000-pound short ton[6]. In US commerce the long ton of 2,240 pounds has only limited use, mainly in restricted industrial fields[6], such as ship displacement and bulk goods like iron ore[2]. The United Kingdom excluded it from trade in 1985 and adopted the tonne of 1,000 kilograms[2]. In most English-speaking countries outside the US, tonne is the standard spelling of the metric unit[4].

Each measure carries its own multiplier. The short ton multiplies by 907.18474. The long ton multiplies by 1,016.0469088. The metric tonne multiplies by 1,000. The Ton type selector changes the multiplier and the unit shown next to the field at the same time, and the result updates as soon as you pick an option.

The long ton is exactly 12% heavier than the short ton[2]. On a 25-ton shipment the short ton gives 22,679.62 kilograms while the long ton gives 25,401.17 kilograms, a difference of 2,721.55 kilograms. When freight is billed by weight, that difference changes the invoice, so pick the ton before you read the result. Single items convert in the kilograms to pounds converter. The same three tons come to 35,273.96, 32,000 and 35,840 avoirdupois ounces, which the tons to ounces converter works out.