How to use BMR Calculator
- Type your weight in the Weight kg (20–400) field.
- Type your height in the Height cm (100–250) field.
- Enter your age as a whole number in Age years (18–100).
- Pick Male coefficient (+5) or Female coefficient (−161) from Equation coefficient.
- Press Calculate to see your estimated resting energy in kcal/day, then Copy result or Reset.
Supported formats and limitations
- Input
- Numbers typed into the form (plain digits, no currency symbols or thousands separators)
- Output
- Result on screen, with one-click copy
- Works on
- Any modern browser on Windows, macOS, Linux, Android and iOS. JavaScript must be enabled.
Important limitations
Results use standard formulas and floating-point arithmetic, shown to a sensible number of decimals. They are estimates for planning and do not replace professional financial, tax, medical or legal advice. Banks and institutions may round differently.
Privacy and file processing
Everything runs in your browser. Nothing you enter is uploaded, stored or logged by this website.
About BMR Calculator
Your basal metabolic rate, or BMR, is an estimate of the energy your body uses at complete rest to keep you breathing, circulating blood and maintaining temperature. This BMR calculator uses the Mifflin-St Jeor equation, widely used by dietitians, and returns the estimate in kilocalories per day. It is a useful starting point if you are planning meals, setting a fitness goal or trying to understand calorie numbers on food labels.
You enter your weight in kilograms, height in centimetres, age in whole years and choose one of two equation coefficients, labelled male and female. The tool is built for adults aged 18 to 100 and checks every value against sensible limits. Keep in mind it estimates rest only; it does not add energy for work, walking or exercise, so daily needs are higher than this number.
Features
- Mifflin-St Jeor formula: 10×kg + 6.25×cm − 5×age + coefficient
- Result in kcal/day
- Range checks: weight 20–400 kg, height 100–250 cm, age 18–100
- Age must be a whole number
- Choice of male (+5) or female (−161) coefficient
Why use it
- A science-based starting point for calorie planning
- Understand how weight and age affect resting energy
- Quick to recheck as your weight changes
- Runs privately on your device
Formula used
Estimated kcal/day = 10×kg + 6.25×cm − 5×age + sex coefficient.
Examples
Male coefficient example
Input: Weight kg: 70, Height cm: 175, Age years: 30, Equation coefficient: Male coefficient (+5)
Result: 1,648.75 kcal/day
Mifflin–St Jeor adult resting-energy estimate, not medical advice.
700 + 1093.75 − 150 + 5 gives an estimated resting energy of about 1,649 kcal.
Female coefficient example
Input: Weight kg: 60, Height cm: 160, Age years: 25, Equation coefficient: Female coefficient (−161)
Result: 1,314 kcal/day
Mifflin–St Jeor adult resting-energy estimate, not medical advice.
600 + 1000 − 125 − 161 gives an estimated resting energy of 1,314 kcal.
BMR Calculator: frequently asked questions
Is BMR the number of calories I should eat each day?
No. BMR is the energy you would burn lying at rest all day. Your real daily needs are higher because you move, work and digest food. Total daily energy is usually estimated by multiplying BMR by an activity factor. Use this figure as a base, and talk to a dietitian for a personal eating plan.
What does the equation coefficient mean?
The Mifflin-St Jeor equation was developed with two constants: +5 for males and −161 for females, reflecting average differences in body composition in the study data. The selector chooses which constant is used in the formula. It is a calculation parameter, not a statement about gender identity.
Why does the tool reject my age or weight?
The equation is meant for adults, so age must be a whole number from 18 to 100. Weight must be 20 to 400 kg and height 100 to 250 cm. Values outside these ranges, decimals in the age field, or text such as kg or cm produce an inline error message instead of a result.
How accurate is the Mifflin-St Jeor estimate?
It is one of the better predictive equations for healthy adults, but it is still an average. Individual results can differ noticeably, especially for very muscular people, older adults, or anyone with a thyroid or other medical condition. Lab methods such as indirect calorimetry measure resting energy directly when precision matters.
Is this calculator medical advice?
No. The result is a general estimate for adults and is not medical or nutritional advice. It may not suit pregnancy, breastfeeding, illness, recovery from surgery or unusual body composition. Please consult a doctor or registered dietitian before making significant changes to your diet or exercise based on this number.
Results are estimates for general information, not financial, medical, legal, tax or property advice. Confirm important figures with the relevant institution or a qualified professional.