tonne

The tonne, symbol t, is a non-SI unit of mass equal to 1,000 kilograms. It is commonly referred to as the metric ton and is used internationally for large masses. Although not an SI base unit, it is accepted for use with the SI.

One tonne equals 1,000,000 grams, and by the SI definition of the kilogram it is exactly 1,000 kilograms. In customary units, 1 tonne is approximately 2,204.6226 pounds. In terms of other tons, 1 tonne is about 0.9842065 long tons (imperial tons) and 1.1023113 short tons (US tons).

The tonne is widely used in science, commerce, and industry for practical measurements of mass. It appears in shipping and freight, construction and manufacturing, agriculture, and energy statistics. It is also used in accounting for emissions, where quantities are often reported in tonnes of CO2 or tonnes of oil equivalent.

Usage and spelling vary by region. In most countries influenced by the metric system, tonne is standard and pronounced similarly to “tonne.” In some English-speaking regions, the word ton or tonnage may be used instead, typically referring to the short or imperial ton. The symbol t is recommended for the tonne, and megaton (Mt) denotes a unit equal to one million tonnes.

Etymology traces the word to the traditional unit ton, with the spelling tonne adopted to reflect its metric basis. The tonne provides a convenient, globally recognized scale for large masses approaching everyday industrial and scientific applications.