The Pandolf equation
Developed by the US Army Research Institute of Environmental Medicine (Pandolf, Givoni and Goldman, 1977), it estimates the metabolic cost of walking with a load:
M = 1.5W + 2.0(W + L)(L/W)² + η(W + L)(1.5V² + 0.35VG)
M = watts · W = body mass (kg) · L = load (kg) · V = speed (m/s) · G = grade (%) · η = terrain factor
M = watts · W = body mass (kg) · L = load (kg) · V = speed (m/s) · G = grade (%) · η = terrain factor
Calories per hour = M × 3600 ÷ 4184. The equation was built for walking speeds; it is less accurate for jogging with a ruck and it does not model downhill walking, so this calculator treats negative grades as flat.
Terrain factors
| Terrain | η |
|---|---|
| Treadmill / paved road | 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 | 2.5 |
| Soft snow 25 cm | 3.3 |
| Soft snow 35 cm | 4.1 |
Rucking calories per hour (flat road, 3.5 mph)
| Body weight | 0 lb ruck | 20 lb ruck | 30 lb ruck | 45 lb ruck | 60 lb ruck |
|---|---|---|---|---|---|
| 130 lb | 262 | 294 | 312 | 343 | 380 |
| 150 lb | 303 | 334 | 351 | 381 | 415 |
| 170 lb | 343 | 374 | 391 | 419 | 452 |
| 190 lb | 384 | 414 | 431 | 458 | 489 |
| 210 lb | 424 | 454 | 471 | 498 | 527 |
| 230 lb | 464 | 494 | 511 | 537 | 566 |
kcal per hour, Pandolf equation, η = 1.0. The 0 lb column is the equation’s estimate for unloaded walking.
Start light. Begin with 10–15 % of body weight and add load or distance gradually — not both in the same week. Use the ruck pace calculator to plan marches.
Last reviewed: September 2026 · Health disclaimer