BMR Calculator

Calories your body needs for basic functions (breathing, circulation, cell production) while completely at rest.

Mifflin-St Jeor for general population. If you know body fat %, Katch-McArdle accounts for lean body mass and can be more precise.

BMR = calories at rest. TDEE = BMR x activity factor = total daily calories including movement and exercise.

Yes, the BMR Calculator is 100% free with no registration, no hidden fees, and no usage limits. All processing happens locally in your browser, ensuring complete privacy.

Absolutely. The BMR Calculator processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the BMR Calculator is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the BMR Calculator in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The BMR Calculator works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

Your BMR is the calories you burn at complete rest, so to find your Total Daily Energy Expenditure (TDEE) you multiply it by an activity factor that reflects how much you move. The five standard levels are sedentary (×1.2) for a desk job with little exercise, lightly active (×1.375) for light exercise 1-3 days a week, moderately active (×1.55) for moderate exercise 3-5 days, very active (×1.725) for hard exercise 6-7 days, and extra active (×1.9) for very hard training plus a physical job. For example, a 1,600-calorie BMR at the moderately active level gives a TDEE of about 2,480 calories. This calculator shows the TDEE estimate for every activity level automatically once it computes your BMR, so you can read your maintenance calories straight off the results.

The Harris-Benedict equation, even in its revised 1984 form, was derived from early metabolic studies and tends to read slightly higher than Mifflin-St Jeor for most people. Mifflin-St Jeor was published in 1990 using a larger, more modern sample and is now widely regarded as the most accurate estimate for the general population, which is why it is shown as the headline BMR here. The gap between them is usually a modest number of calories rather than a dramatic difference, but it matters if you are setting a tight calorie target. This tool runs both equations side by side and shows exactly how many calories each one differs from Mifflin-St Jeor, so you can see whether the methods agree before you trust a single figure. Enter your details to compare them instantly.

No. The two default equations, Mifflin-St Jeor and Harris-Benedict, only need your sex, age, weight, and height, so you can get a solid BMR estimate without any body composition data. Body fat percentage becomes useful for the lean-mass formulas: Katch-McArdle (370 + 21.6 × lean body mass) and Cunningham (500 + 22 × lean body mass) both calculate from lean mass rather than total weight, so they need your body fat number to work. Because they account for how muscular you are, they can be more precise for athletes and lean individuals whom population formulas tend to underestimate. In this calculator those two formulas stay blank until you add a body fat percentage, then unlock automatically. Start with just the basics, and add body fat later if you want the lean-mass comparison.

Every BMR formula is an estimate built from population averages, so it gives you a well-grounded starting point rather than a clinical measurement. Real metabolism varies with genetics, hormones, thyroid function, medications, and medical conditions, which is why two people with identical stats can burn different amounts at rest. The only truly precise method is indirect calorimetry done in a lab. For most people the equation-based estimate is close enough to plan calorie targets, especially the Mifflin-St Jeor formula used as the default here. Running four formulas side by side helps too: when they cluster tightly you can be more confident, and when they spread apart you know to treat the number cautiously. Use this calculator to get your baseline, then adjust based on real-world results over a few weeks, and consult a professional before any major dietary change.

You should not eat below your BMR for sustained periods, because that is the energy your body needs just to keep its organs running. Weight loss is driven by a deficit below your maintenance calories (TDEE), not below your resting BMR. A common approach is to subtract a few hundred calories from your TDEE, since roughly a 500-calorie daily deficit corresponds to about a pound of fat loss per week. Cutting too aggressively can leave you under your BMR, which often backfires through fatigue, muscle loss, and a stalled metabolism. This calculator gives you both numbers: your BMR floor and your TDEE for each activity level, so you can set a sensible deficit from maintenance rather than from rest. For detailed macros, the linked TDEE calculator extends these figures.