The Trouble with Tons
a freighter

When it comes to trade, keeping all the different types of tons straight can be tricky. That's why having an international standard is so critical.


The word "ton" is ambiguous, because it can be used in reference to multiple weights. There is the short ton, for example, which is equal to 2,000 pounds or about 907 kilograms. Then there is the long ton, which is 2,240 pounds, or about 1,016 kilograms. Finally, the word "ton" can also be used in reference to what is commonly known in the United States as the metric ton, which is assigned the official symbol "t" in the International System of Units. That's 1,000 kilograms, or about 2,204 pounds [source: U.S. Metric Association]. You may also see the word "ton" spelled as "tonne" although technically, the correct metric term for 1,000 kilograms is a megagram -- denoted by the symbol Mg.

Speaking of kilograms, let's look closer at them on the next page.