Resting Metabolic Rate (Owen) Calculator

How it is calculated

This is the simplest resting-energy equation in the set: one straight line per sex and a single input, body weight in kilograms. Men: RMR = 879 + 10.2 × weight. Women: RMR = 795 + 7.18 × weight. The result is in kcal per day. The tool then multiplies RMR by 1.2 for a sedentary total and by 1.55 for an active total, and rounds all three numbers to whole kcal. Height, age and body composition are not inputs, so two women of equal weight always get the same answer. The constant term is large, which means a very light person still gets a high estimate. Weights outside 2–650 kg give no result. Any sex value other than female is treated as male.

Common mistakes

• Entering weight in pounds; the slope is per kilogram, so 132 lb typed for a 60 kg woman gives 1,743 kcal/day instead of 1,226, about 40% too high.
• Treating the active figure as a weight-loss intake: it is estimated maintenance, so any deficit must come off it.
• Expecting age, height or muscle to move the number; with weight as the only input, an older small-framed person and a young tall one are scored the same.
• Ignoring the sex switch: leaving it on male for a woman adds 84 kcal plus 3.02 kcal for every kilogram (265 kcal at 60 kg).