Pandolf equation

The Pandolf equation is an empirical equation for predicting the metabolic cost of load carriage. It was first published in 1977 for estimating energy expenditure while standing or walking slowly with an external load.^[1]

In this equation, ${\displaystyle M}$ is the metabolic rate (in watts), ${\displaystyle W}$ is body mass (in kilograms), ${\displaystyle L}$ is the external load mass (in kilograms), ${\displaystyle V}$ is walking velocity (in meters per second), ${\displaystyle G}$ is the grade (percent slope), and ${\displaystyle \eta }$ is a dimensionless terrain factor accounting for surface conditions. The first term estimates standing metabolic cost without load, the second accounts for standing with a carried load, and the third is the velocity-dependent walking term.

Common values for the terrain factor ${\displaystyle \eta }$ include:^[2][3]

Terrain factor values

Surface	${\displaystyle \eta }$
Blacktop road or treadmill	1.0
Dirt road	1.1
Light brush	1.2
Heavy brush	1.5
Swampy bog	1.8
Loose sand	2.1
Soft snow, 15 cm depth	2.5
Soft snow, 25 cm depth	3.3
Soft snow, 35 cm depth	4.1