Weight converter

The United States uses the short ton (2,000 lb), while the United Kingdom historically used the long ton (2,240 lb) in shipping and trade — the two differ by about 12%, so mixing them up in a real calculation matters. Metric tonnes (1,000 kg, sometimes written "metric ton") are a third, unrelated unit that happens to sound similar. This calculator keeps all three separate rather than assuming "ton" means one specific thing.

Stone is used in the UK and Ireland for body weight but almost nowhere else — one stone is exactly 14 pounds. It's almost always expressed as a pair, e.g. "11 stone 6", rather than as a decimal stone value, which is why this calculator gives stone and pounds their own linked pair of fields instead of a single stone field.

This calculator uses grams as the common reference point and converts to and from it, regardless of which field you actually type into: 1 kg = 1,000 g, 1 tonne = 1,000,000 g, 1 lb = 453.59237 g, 1 oz = 28.34952 g, 1 US short ton = 907,184.74 g, and 1 UK long ton = 1,016,046.91 g.

A physical mass is always zero or positive — there's no such thing as −5 kilograms of anything. If you enter a negative value, this calculator flags it as invalid rather than propagating a meaningless negative figure across every other unit.