How this calculator works
This page uses the Mifflin-St Jeor equation, a resting energy estimate for healthy, non-pregnant adults; this tool accepts ages 15 to 100, though the original study covered ages 19 to 78. It estimates the energy your body uses at complete rest for basic functions over 24 hours. The original study found the older Harris-Benedict equations overestimated needs by about 5 percent, and errors grow for older adults and athletes. The result is an estimate for information only and is not medical advice.
Formula
Men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age(years) + 5. Women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age(years) - 161. Results in kcal/day.
Worked example
A 30-year-old man weighing 80 kg at 180 cm: BMR = 10 x 80 + 6.25 x 180 - 5 x 30 + 5 = 1780 kcal/day. A 55-year-old woman weighing 72 kg at 160 cm: BMR = 720 + 1000 - 275 - 161 = 1284 kcal/day.
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Frequently asked questions
What is the difference between BMR and TDEE?
BMR is resting energy only. Total daily energy expenditure multiplies BMR by an activity factor; the TDEE calculator does that step for you.
Why is there no input for body fat?
Mifflin-St Jeor predicts from weight, height, age and sex alone. Formulas that use lean mass, such as Katch-McArdle, need a body fat measurement this page does not ask for.
Is the estimate reliable for everyone?
No. It was developed on healthy adults and is least accurate for people under 15, over about 70, very muscular, or living with illness. Individual resting metabolism varies.