--- title: "BMR Calculator - Basal Metabolic Rate | CanDoYa" description: "Free BMR calculator using the Mifflin-St Jeor equation. Estimate resting calories from age, sex, height and weight in metric or US units." url: https://candoya.com/tools/bmr-calculator/ locale: en type: browser-tool --- # BMR Calculator Category: Calculators ## What is a BMR calculator? A BMR calculator estimates how many calories your body uses each day at rest to support breathing, circulation, temperature control and other basic functions. This calculator applies the Mifflin-St Jeor equation to your age, height, weight and sex, then shows the result in calories and kilojoules per day. Choose metric or imperial units and the estimate updates as you type. The calculation happens locally in your browser, with no account or upload. The result is your resting baseline, not your full daily calorie need. Activity, digestion and exercise belong in a separate TDEE calculation. ## How to use it 1. **Choose your units** - Select metric for centimetres and kilograms, or imperial for feet, inches and pounds. 2. **Enter your details** - Choose the sex constant used by the equation, then enter your adult age, height and weight. 3. **Read the live estimate** - See your BMR in calories per day, calories per hour and kilojoules per day, plus the exact formula working. 4. **Copy the estimate** - Copy the result and formula if you want to save or compare it. Treat it as an estimate, not a prescribed intake. ## Who it's for - **People planning meals** who want a resting calorie baseline before considering activity. - **Fitness beginners** comparing BMR with total daily energy expenditure instead of treating them as the same number. - **Coaches and students** checking the Mifflin-St Jeor working with a clear, reproducible formula. - **Metric and US unit users** who want the same calculation without converting height and weight first. ## Expert note Online BMR calculators usually estimate resting energy expenditure rather than measure a strict laboratory BMR. The Mifflin-St Jeor equation was derived from adults aged 19 to 78, so an estimate can differ from indirect calorimetry and should not be treated as a personal diagnosis. ## Frequently asked questions ### Is this BMR calculator free and private? Yes. The calculator is free, needs no account and performs the formula entirely in your browser. Your age, height and weight are not uploaded for the calculation. You can clear the fields at any time and there is no calculation limit. ### What is the Mifflin-St Jeor BMR formula? For males, the equation is 10 times weight in kilograms plus 6.25 times height in centimetres minus 5 times age, plus 5. For females, the final constant is minus 161 instead. The calculator converts imperial measurements to metric before applying the same equation. ### How accurate is a BMR calculator? A BMR formula gives a population-based estimate, not a direct measurement. The Mifflin-St Jeor equation is widely used for adults, but muscle mass, health conditions, medications and individual biology can shift actual resting energy use. Indirect calorimetry in a clinical setting provides a measured value. ### Is BMR the same as TDEE? No. BMR estimates energy used at rest for essential body functions. TDEE estimates your full daily energy expenditure by accounting for activity and other energy use. Your TDEE should normally be higher than your BMR, so do not use the resting number as a maintenance calorie target. ### Can I use the BMR calculator to lose weight? Use BMR as one input, not as a weight-loss target. A practical calorie plan starts with estimated total daily energy expenditure, then considers a moderate deficit and your health needs. A registered dietitian or clinician can help if you have medical conditions or a history of disordered eating. ### Can children use the BMR calculator? This version is intended for adults aged 18 and older. Children and teenagers have changing energy needs and are better assessed with age-specific pediatric methods. Ask a pediatric clinician or dietitian for guidance instead of relying on an adult Mifflin-St Jeor estimate. ## Related tools - [BMI Calculator](https://candoya.com/tools/bmi-calculator/) - [Calories Burned by Activity Calculator](https://candoya.com/tools/calories-burned-by-activity/) - [TDEE Calculator](https://candoya.com/tools/tdee-calculator/) --- *Markdown edition of , published for AI agents and other automated readers. Index of key pages: .*