What Is the Pandolf Equation for Rucking?
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The Pandolf equation is a load-carriage model that estimates metabolic power during standing or walking with an external backpack load. CalculatorGeek uses it to estimate energy cost, not to diagnose fitness or measure an individual’s exact calorie burn.
Pandolf equation: direct answer
The model combines body mass, pack load, walking speed, uphill grade, and a documented terrain factor. It returns watts, which can be converted to kilocalories per hour and then multiplied by moving duration.
The Pandolf formula
M = 1.5W + 2(W + L)(L/W)2 + η(W + L)(1.5V2 + 0.35VG)
This implementation uses the published equation without an unexplained recreational adjustment or universal uplift.
Variables and units
- M
- Modeled metabolic power in watts.
- W
- Body mass in kilograms.
- L
- Backpack load in kilograms.
- V
- Walking speed in meters per second.
- G
- Uphill grade entered as a percentage, so 5 means 5%.
- η
- Terrain factor: 1.0 firm surface, 1.1 dirt road, 1.2 light brush, 1.5 heavy brush, 1.8 swampy bog, or 2.1 loose sand.
Why it is useful for rucking
Generic walking estimates usually do not ask for a pack load or terrain. Pandolf includes both, making it useful for comparing two loaded walks when the same method and realistic route inputs are used.
Try the Rucking Calorie Calculator, then change one input at a time to see how it affects the modeled result.
What it cannot tell you
The equation cannot confirm personal calorie burn, readiness, injury risk, food requirements, or the safety of a pack weight. It does not reliably model downhill walking, running, weighted-vest load distribution, weather, changing route conditions, or fatigue over prolonged sessions.
A 2017 validation study found under-prediction across its tested contemporary military speed-and-load conditions, with prediction error varying by condition. Read the accuracy guide before treating a result as precise.
Worked example
For an 80 kg person carrying 15 kg at 1.5 m/s on a level firm surface, the inputs are W = 80, L = 15, V = 1.5, G = 0, and η = 1.0. The equation returns approximately 447 W, equivalent to about 385 kcal per hour.
Methodology, sources, and review
Reviewed by the CalculatorGeek Expert Review Team on September 7, 2026. The team checked the published formula, units, terrain factors, supported boundaries, gross-energy convention, worked examples, cited limitations, and reciprocal cluster links. Material formula or source changes require another recorded review.
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