BMR Calculator

The BMR Calculator estimates your Basal Metabolic Rate — the number of calories your body burns at complete rest just to keep basic life-sustaining functions running, including breathing, circulation, cell production, and temperature regulation. Your BMR represents the largest single component of your total daily calorie expenditure, typically accounting for sixty to seventy-five percent of the energy you use each day. Enter your age, sex, height, and weight, and the tool computes your BMR using both the Mifflin–St Jeor and the Harris–Benedict equations so you can compare the two most recognized formulas side by side. The Mifflin–St Jeor equation, developed in 1990, is generally considered the more accurate of the two for modern populations and is the formula recommended by the Academy of Nutrition and Dietetics for clinical use. The Harris–Benedict equation, originally published in 1919 and revised in 1984, remains widely cited in textbooks and older research. Seeing both results helps you understand the range of your estimated resting metabolism and choose the figure that best matches your circumstances. Knowing your BMR is the first step in building any calorie-aware plan: multiply it by an activity factor to get your TDEE, then adjust up or down depending on whether your goal is maintenance, fat loss, or muscle gain. The calculator is valuable for dietitians creating client meal plans, athletes periodizing nutrition around training phases, medical professionals assessing resting energy needs, and individuals who want a science-based starting point for calorie tracking. You can toggle between metric and imperial units. All math executes inside your browser — your personal measurements are never transmitted or stored. No accounts, no ads, and no usage restrictions. Recalculate whenever your weight changes to keep your nutrition targets current.

1. Enter your age, sex, height, and weight.
2. Choose metric or imperial units.
3. Compare your BMR from the Mifflin-St Jeor and Harris-Benedict equations.
4. Use the result as the baseline for TDEE and calorie planning.

Basal metabolic rate is the energy your body burns at complete rest just to stay alive — the foundation of any calorie plan. Seeing two well-known formulas side by side helps you gauge a sensible range rather than trusting a single number.

• Two respected formulas: Mifflin-St Jeor and Harris-Benedict.
• Side-by-side comparison of both estimates.
• Metric and imperial input support.
• A clean baseline number to feed into TDEE and macro planning.
• Calculated in your browser — no personal data leaves the page.

Mifflin-St Jeor (more accurate for modern populations): BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 for men, or − 161 for women. Harris-Benedict (revised): for men, BMR = 88.362 + 13.397 × weight(kg) + 4.799 × height(cm) − 5.677 × age; for women, BMR = 447.593 + 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age. The two often differ by 50–150 kcal.