How We Calculate Animal Horsepower

To estimate the horsepower of animals, we use a "combined method" that incorporates both mechanical power output and biological energy efficiency based on Kleiber's Law.

1. Mechanical Power Calculation

Mechanical power is calculated using the formula based on the animal's weight and maximum speed:

Formula:
Horsepower = (Weight (kg) × Speed (m/s)2) / 5400

2. Kleiber's Law: Metabolic Power

Kleiber's Law describes the relationship between an animal's mass and its basal metabolic rate.

Formula:
Power (W) = 70 × Mass (kg)0.75
Horsepower = Power (W) / 745.7

3. The Combined Formula

We combine the "mechanical power" and "metabolic power" for a balanced estimate of an animal's overall horsepower.

Combined Horsepower = (0.6 × Mechanical Horsepower) + (0.4 × Metabolic Horsepower)

Example Calculations

Let's take a few animals to illustrate how the combined method works:

Elephant (6000 kg, 40 km/h)

Cheetah (72 kg, 120 km/h)

Falcon (1.2 kg, 390 km/h)

Sources and References