How to Calculate Weight to HP Ratio

A vehicle's speed is affected by its weight-to-hp ratio.

The weight-to-horsepower ratio of a car, truck or motorcycle is one of the most significant determining factors of that vehicle's speed. Calculating this ratio is a simple, single-step process that should require little more than consulting your vehicle's owner's manual and pressing a few calculator buttons. An engine with more horsepower is technically more powerful, but this extra power means little if the vehicle in which it is mounted is also heavier. The weight-to-horsepower ratio gives a better notion of your vehicle's overall power than considering the horsepower alone, because it takes into account the vehicle's weight.

Instructions

1. Consult the owner's manual of your vehicle to find its weight and horsepower. Most owner's manuals contain an appendix of general information about the vehicle toward the front or back of the book.

2. Divide the vehicle's total weight by the horsepower. The number you find is the weight-to-horsepower ratio.

3. Compare your vehicle's ratio to that of other vehicles to get a better idea of your vehicle's overall capacity for speed. According to Tom Magliozzi of National Public Radio's "Car Talk," most cars have a weight-to-horsepower ratio below .06. Sport cars may have significantly higher ratios.

References

• Stealth 316: Calculations
• Car Talk: Enough Is Enough!