What a loaded ruck actually costs you per hour
The hardest thing to judge before a field exercise or a long march is how much the ruck itself adds. Enter body weight, ruck weight, walking speed, uphill grade, terrain and distance, and this page returns the metabolic rate in watts, converts it to energy per hour and per minute, and totals the march. It also recomputes the same walk with the ruck removed, so the extra cost of carrying the load appears as a percentage rather than a guess.
The calculation uses the Pandolf, Givoni and Goldman load-carriage equation. Speed is converted to metres per second and grade is used as a percentage, as that equation requires, and the terrain factors come from the Soule and Goldman set: paved road 1.0, dirt road 1.1, light brush 1.2, heavy brush 1.5, swampy bog 1.8 and loose sand 2.1. Watts are turned into calories using 4,184 joules per kilocalorie (as of October 2026).
The limits are real. Under heavy loads and faster speeds the equation has been reported to fall 12 to 33 percent below measured values, so treat the output as a floor rather than a ceiling. Downhill walking is outside its range, which is why negative grades are rejected instead of guessed at. Heat, humidity, lost sleep and dehydration are not in the equation at all, and those are what usually put people down on a real march. Plan water and halts first, and stop and get medical support at the first sign of heat illness.
Frequently asked questions
Under heavy loads and faster speeds this equation has been reported to run 12 to 33 percent below measured values, so it is safer to read the result as a floor.
No. The equation covers level and uphill walking and has no downhill correction, so a negative grade returns a message instead of a number.
Pick the surface you will actually walk on. Paved road is the lowest at 1.0 and loose sand the highest at 2.1, so the same ruck can cost more than twice as much on sand.