How this calculator works
Divide rated power by the mass included in your comparison. Use the same convention for each vehicle: engine-only mass and fully loaded vehicle mass give very different figures. This ratio does not predict acceleration by itself because traction, gearing, resistance and speed also matter.
Formula
R = P/m. 1 mechanical hp = 745.6998715822702 W; 1 lb = 0.45359237 kg.
Worked example
100 kW and 1000 kg give 100 W/kg or 0.1 kW/kg. Doubling mass to 2000 kg gives 50 W/kg.
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Frequently asked questions
Is weight measured in newtons here?
No. The familiar name uses weight informally; this tool divides power by mass.
Which horsepower is used?
Mechanical horsepower, rather than metric horsepower.
Should I use peak or continuous power?
Choose the rating relevant to your comparison and use that same rating for every system.