BMR Calculator — Basal Metabolic Rate
BMR Calculator
Estimate the energy your body needs at rest, compare established formulas, and understand how resting metabolism differs from your total daily calorie needs.
← Explore all free toolsCalculate your resting energy
Enter your age, height, and weight. Optional body-fat information enables an additional formula comparison.
These prediction formulas were developed with female/male physiological categories. Neither option perfectly describes everyone; hormone therapy and body composition may affect accuracy.
If you have a body-fat estimate, we’ll also calculate a Katch–McArdle result. Body-fat measurements themselves may be imprecise, so this isn’t automatically the better estimate.
These broad activity multipliers can miss individual differences. For more detailed planning, use our TDEE calculator.
Your resting-energy snapshot
kcal / day · resting estimate, not a food target
Compare the formulas
Differences are expected. These are predictions, not measured metabolic rates.
Resting energy and your whole day
Choose an activity level above to see a broad daily-energy illustration.
What affects this estimate?
Larger bodies generally need more resting energy, although composition and health also matter.
Population averages change with age, but a single age cannot fully predict anyone’s metabolism.
Illness, medications, hormones, and measurement conditions can affect actual results. Indirect calorimetry is used when a measured RMR is needed.
BMR vs. TDEE: what should you use?
Resting energy is just one part of the daily picture. Online BMR formulas are commonly used to estimate what a body expends at rest, while TDEE estimates include routine movement, exercise, and digestion. If your goal is to plan food intake, begin with a realistic estimate of total daily energy rather than interpreting your BMR as a daily calorie target.
You can also explore how calorie estimates relate to food intake using our calorie deficit calculator, or learn the basics in our calorie deficit guide. A prediction equation cannot establish whether someone has a medical metabolic condition.
Explore related wellness tools
Use each tool for a different part of the picture rather than treating one number as the answer.
Method & references
The headline result uses the Mifflin–St Jeor resting-energy equation. Revised Harris–Benedict and optional Katch–McArdle estimates are shown for comparison. All are approximations and can differ substantially from measured resting expenditure. The female/male coefficients are built into the published equations; individual needs do not fall neatly into two categories.
Mifflin et al., 1990 (original equation) · Frankenfield et al., 2005 (systematic review) · 2016 cross-validation study
Educational information for adults. This tool does not diagnose a slow metabolism or recommend a diet, treatment, or calorie restriction. For individualized guidance or special medical circumstances, consult a qualified healthcare professional. No personal inputs are stored by this tool.