What Is the Average Horsepower for a Lawnmower?

In its most basic form, horsepower is a measure of work: 1 horsepower is the amount of work required to move 33,000 pounds 1 foot over the space of 1 minute. A lawnmower with higher horsepower can typically do more work faster than a comparable mower with a lower horsepower rating. Lawnmower industry standards are changing, and some manufacturers, such as Briggs & Stratton and Troy-Bilt, rate their engines by gross torque rather than horsepower.

If you are in good physical condition and have a lawn smaller than 1/4 acre, a push mower will usually be sufficient to keep your grass in top shape. Low-cost push lawnmowers typically have engines with horsepower ratings of between 2.9 and 4.0. A self-propelled model might be more appropriate if you have up to 1/2 acre to mow, but these models need greater horsepower to help with the increased workload. These so-called walk-behind lawnmowers come with engines with average horsepower ratings of from 5.0 to 7.0.

Trying to mow a lawn that is larger than 1/2 acre with a push mower, or even a self-propelled model, can be both time consuming and physically exhausting. A lawn tractor, sometimes referred to as a riding lawnmower, might be the answer. The average horsepower ratings on riding lawnmowers range from 12.5 to 20.0. A mower on the lower end of the horsepower average might be fine if your lawn is smaller, flat and level -- but if you have a lot of ground to cover and the terrain is hilly or on an incline, selecting a model with higher horsepower might be your best bet.

A relatively new development in lawn care is the stand-on mower, sometimes called a surfer. It's something of a hybrid between a walk-behind and a riding lawnmower. You stand on a platform behind the mower deck and ride the mower. Surfers are faster than walk-behind mowers and less expensive than comparable riding mowers. The average engine on a surfer-style mower is rated between 19 and 23 horsepower.