# How to Calculate Power-to-Weight Ratio

by Ayub SuleimanUpdated March 16, 2018
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The power-to-weight ratio is a common expression used when discussing the relative power of an engine. Since most engines are attached to vehicles that move, the weight of the vehicle on which the engine is mounted must be included in the calculation of the power-to-weight ratio. The power-to-weight ratio is significant because it allows different vehicles to be compared, based on the relative power of each.

### Find the Power

Find the power of the engine for which you are calculating the power-to-weight ratio.

Write down the power in the units specified.

Convert the unit to horsepower, watts or newtons, as per your preference.

### Find the Weight

Find the weight of the vehicle or engine.

Write down the weight. Convert the weight to kilograms, pounds or the unit of your preference.

Divide the power by the weight. This is the power-to-weight ratio as per the units you selected.

### Items you will need

• Pencil

• Paper

• Calculator

#### Tips

The units can be converted easily once you find the conversion algorithms. Conversion algorithms are available online.

The completed power-to-weight ratio is expressed in the units you chose to calculate.

The power-to-weight ratio will reflect only the power-to-weight ratio of the engine alone if you do not find the net weight of the vehicle before calculating.

• Pencil
• Paper
• Calculator