BMR Calculator

The three BMR equations, written out

• Mifflin-St Jeor, men: BMR = 10 × W + 6.25 × H − 5 × A + 5
• Mifflin-St Jeor, women: BMR = 10 × W + 6.25 × H − 5 × A − 161
• Revised Harris-Benedict, men: BMR = 88.362 + 13.397 × W + 4.799 × H − 5.677 × A
• Revised Harris-Benedict, women: BMR = 447.593 + 9.247 × W + 3.098 × H − 4.330 × A
• Katch-McArdle, all adults: BMR = 370 + 21.6 × LBM, where lean body mass LBM = W × (1 − body fat % ÷ 100)

Mifflin-St Jeor was published in 1990. The revised Harris-Benedict equation is the 1984 update by Roza and Shizgal of the original Harris-Benedict equation from 1918. Katch-McArdle does not use age or sex, because it is based only on lean mass.

Worked example with all three formulas

The three results differ by up to 73 kcal per day. The calculator rounds BMR to a whole number before it multiplies by your activity factor. At the Moderate level (× 1.55), these become TDEE values of 2,702, 2,815 and 2,716 kcal.

When to use which formula

• Mifflin-St Jeor (default): the best choice for most healthy adults. In a large review, it predicted resting energy within 10% of the measured value for more people than other common equations.
• Revised Harris-Benedict: useful if you want to compare with older tools, or if your dietitian uses it. It often gives a higher number than Mifflin-St Jeor, as in the example above.
• Katch-McArdle: use it only when your body fat % comes from a reliable method, such as a DEXA scan or skinfold tests by a trained person. A wrong body fat guess gives a wrong lean mass and a wrong BMR.

To use Katch-McArdle in the calculator, open Advanced options, choose it as the BMR formula and enter your body fat %. If you choose Katch-McArdle but leave body fat empty, the calculator uses Mifflin-St Jeor. Read the full comparison in Mifflin-St Jeor vs Harris-Benedict.

BMR vs RMR vs TDEE

• BMR (basal metabolic rate): energy used at complete rest under strict lab conditions: in the morning after sleep, about 12 hours after the last meal, lying still in a comfortable room.
• RMR (resting metabolic rate), also called resting energy expenditure (REE): energy used at rest under less strict conditions. It is usually slightly higher than BMR.
• TDEE (total daily energy expenditure): BMR plus all movement, exercise and digestion over a full day. Base your eating plan on this number, using the TDEE calculator.

The equations on this page were developed from resting measurements, so the terms BMR and RMR are often used for the same thing. For meal planning, the small difference does not matter much.