Following the success of our “Difference between SWL/WLL/MRC” article around the world, another area of confusion is the difference between a Ton and a tonne.
Let’s be clear from the start: ‘Ton’ and ‘tonne’ are not equal, and it’s not just about the spelling.
Both are a unit of weight, a Ton is an Imperial measurement (still widely used in the USA), and a tonne is a Metric measurement.
However, they’re not interchangable for each other. Each has a different weight, ascribed by the International System of Units (SI), where officially a tonne is called a Megagram or one million grams or one thousand kilograms.
Which one is heavier depends on where you live.
Ton vs tonne, so what’s the difference between the Imperial and Metric Ton?
To further complicate things, a Ton may relate to two different weights. In the United States, they measure by the US Ton or short Ton, while the British Ton, known as an Imperial Ton or long Ton is heavier.
- A short Ton is the US customary version, is equal to 2,000 pounds
- A long Ton is the mostly outdated Imperial Ton, is equal to 2,240 pounds
- A tonne, also known as a metric Ton, is equal to 1000kg, (or 2,204.6 pounds)
Both the long and short Tons are a measure representing 20 hundredweight.
What is a hundredweight? That’s 100 pounds (US) or 112 pounds (UK). As the UK has moved to the Metric system, the British or long Ton is no longer officially used, although there is evidence of the word “Ton” or “T” still on many cranes, hoists and lifting apparatus. The US maintains their customary short Ton.
So, an Imperial Ton that was used in Australia is 36lbs or 16kg heavier than a metric tonne. If you lived in America, the metric tonne is 204lbs or 91kg heavier than the US Ton.
When representing an Imperial Ton with one letter it is customary to use a capital “T” whereas to indicate metric tonnes then a lower case “t” is used.
If you are spelling the word Ton or tonne then it can be either capitals or lower case if you spell the whole word.
Why does Ton vs tonne matter?
The difference between measuring in Metric or Imperial has implications in international trade, especially in large projects with many moving parts.
In 1999, NASA lost a $125 million Mars orbiter because of a Metric/Imperial confusion. Reports stated that a contracted engineering team used the English units of measurement ,while the agency’s team used the metric system. The results are now strewn across the surface of Mars.
What is the origin of the word tonne?
Ton and tonne both originate from Germanic in the Middle Ages. ‘Tun’ became the standard word for the wine cask volume measurement, equivalent to 954 litres. These enormous barrels would have weighed very close to the modern day tonne.
We also have the French to thank for standardising the metric system, including creating the first metre following the French Revolution.
Is it Ton or tonne in Australia?
As with the majority of the world’s nations which have adopted the Metric system, go with tonne. If you’re in the US, the easy way to remember it is 2000lbs is a Ton, while 1000kg is a tonne (or metric Ton).
Hopefully, now it’s easier to work out which is heavier; a Ton of feathers or a tonne of bricks.