Animal Power aims to increase the diversity in rating machines - horses should not have exclusive claims to being the standard for power.
Horsepower is normally used to judge cars and trucks, but this page doesn't discriminate on the use of the power - it can be used for vehicles or water pumps or whatever, as long as you know its horsepower rating.
Enter a number (such as the horsepower of your gizmo) in the Power field, select an animal from the dropdown list, and then click the Convert button.