Ton vs Tonne
A US short ton is 2,000 pounds (907.18 kg), a UK long ton is 2,240 pounds (1,016.05 kg), and a metric tonne is 1,000 kilograms (2,204.62 lb).
By Piero Nanni · Last checked
The three units side by side
The spread between the smallest and largest is about 12 percent. On a single shipping container that is well over a tonne of difference, which is why freight documents specify which ton they mean rather than relying on context.
| Unit | Definition | In kilograms | In pounds | Used in |
|---|---|---|---|---|
| Short ton (US ton) | 2,000 lb | 907.18474 kg | 2,000 lb | United States |
| Long ton (imperial ton) | 2,240 lb | 1,016.0469 kg | 2,240 lb | UK, historically |
| Metric tonne | 1,000 kg | 1,000 kg | 2,204.62 lb | Everywhere else, and international trade |
Why the long ton is 2,240 pounds
The odd-looking 2,240 comes from the hundredweight. In the imperial system a hundredweight is 112 pounds, not 100, because it was defined as eight stone of 14 pounds each. Twenty hundredweight make a ton, and 20 × 112 is 2,240.
The United States kept the ton at 20 hundredweight but redefined the hundredweight as a round 100 pounds, giving the 2,000 pound short ton. Both systems are internally consistent; they simply disagree about what a hundredweight is.
How to tell which one a document means
The spelling is a weak signal. British English often writes "tonne" for the metric unit and "ton" for the imperial one, but American English writes "ton" for both and relies on context, and plenty of documents are inconsistent.
The reliable signals are the symbol and the size of the number. The metric tonne is written "t", the short ton is usually "ST" or "sh tn", and the long ton is "LT". If a figure is quoted to a suspiciously round number of thousands, it is almost certainly metric.
One place the distinction is load-bearing rather than pedantic: carbon accounting. Emissions figures are quoted in metric tonnes of CO₂ equivalent, so reading a US-sourced "tons" figure as tonnes understates it by about 10 percent.
Frequently Asked Questions
Is a ton the same as a tonne?
No. A metric tonne is 1,000 kg. A US short ton is 907.18 kg and a UK long ton is 1,016.05 kg.
Which ton is bigger?
The long ton at 1,016.05 kg, followed by the metric tonne at 1,000 kg, then the short ton at 907.18 kg.
How many pounds are in a metric tonne?
One metric tonne is 2,204.62 pounds.
What does "MT" mean on a shipping document?
Usually metric tonne, though it is ambiguous enough that careful documents write "t" or spell it out.