Everybody advertises a vehicle's horsepower, but horsepower by itself doesn't mean much. A heavy vehicle can bog down a high horsepower, resulting in poor performance. Likewise, a lighter vehicle doesn't need as much horsepower to go very fast. To take into account the weight of the car, performance enthusiasts frequently cite horsepower per ton. This gives a more accurate picture of a vehicle's performance by taking into account the horsepower as it relates to the weight it must move.

Look up the vehicle's horsepower and weight in kilograms. These are usually available in the manufacturer's brochure or specification sheet.

Convert kilograms into metric tons, which are most frequently used when calculating horsepower/ton. One metric ton equals 1,000 kilograms, so just divide the number of kilograms by 1,000 to get the number of metric tons, or tonnes.

Divide the horsepower by the weight in metric tons. As an example, if you had a 400hp car that weighed 1.5 metric tons, then it would have 267hp/ton. If you had a 200 horsepower motorcycle that weighed just 200kg (0.200 metric tons), it would have 1,000hp/ton. Notice that the motorcycle has nearly four times as much horsepower per metric ton, even though it technically has half the actual horsepower.