BMR Calculator – Basal Metabolic Rate

Use our free BMR calculator to find your basal metabolic rate (BMR), or resting metabolic rate (RMR), in seconds. Enter your sex, age, height and weight to see how many calories your body burns at rest.

A basal metabolic rate calculator estimates the minimum calories your body needs at rest to maintain life functions (breathing, circulation, cell repair). Our BMR calculator uses the widely used Mifflin-St Jeor formula and works as an online BMR calculator for both women and men. Knowing your BMR is the first step toward planning your daily calorie intake; use our TDEE calculator next to get your total daily energy expenditure. You can enter your height and weight in metric (cm, kg) or imperial (ft/in, lb); we convert everything internally to metric for the formula.

Units

What is BMR?

BMR stands for basal metabolic rate. It is the number of calories your body burns at complete rest to keep you alive–breathing, circulating blood, maintaining body temperature, and supporting basic cell functions. A BMR calculator gives you an estimate of this resting metabolic rate. BMR does not include calories burned by activity, digestion, or exercise; for that, you need a TDEE (total daily energy expenditure) calculator. Our basal metabolic rate calculator uses the Mifflin-St Jeor equation, one of the most accurate formulas for most adults.

How to Calculate BMR

You can calculate your BMR online with the form above. Enter your sex, age in years, height in centimetres, and weight in kilograms, then click "Calculate BMR". The calculator uses the Mifflin-St Jeor formula to estimate your basal metabolic rate. This resting metabolic rate calculator works for both women and men; the formula is the same, with a different constant for each sex.

BMR formula (Mifflin-St Jeor)

The Mifflin-St Jeor equation is one of the most accurate BMR formulas for adults. Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5. Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161. BMR is expressed in kilocalories per day (kcal/day). Some people also refer to resting metabolic rate (RMR); RMR and BMR are very similar–both measure calories at rest. This BMR calculator gives you an estimate suitable for most uses; for personalised values, professional testing is available.

BMR for Women and Men

There is no separate BMR calculator for women and men in terms of how you use it–you enter the same data (sex, age, height, weight) and get your result. The formula is the same; only the constant at the end differs: men use +5, women use −161. So whether you're looking for a BMR calculator for women or a BMR calculator for men, this tool works for both. BMR tends to be lower in women than in men of the same age and size, mainly due to body composition differences; the formula accounts for that.

BMR and TDEE – What Next?

Your BMR is only part of your daily calorie needs. To lose weight, maintain weight, or gain weight, you need to know your TDEE (total daily energy expenditure)–calories burned at rest plus all activity. Use our TDEE calculator after you have your BMR: it multiplies your BMR by an activity factor to give you total daily calories. Then you can plan a calorie deficit to lose weight or a surplus to gain. BMR to lose weight is not enough on its own; basing your diet on TDEE is more accurate.

When to Recalculate BMR

Recalculate your BMR when your weight changes significantly (for example by 5 kg or more), when your activity level changes, or every few months if you're tracking your progress. Because the formula uses weight, height, age, and sex, any big change in weight will change your BMR estimate. Recalculating helps you keep your diet and calorie targets up to date.

Limitations and Disclaimer

This BMR calculator is for screening and information only. It uses a formula that works well for most adults; accuracy is typically around 90–95% and individual variation exists. It does not replace professional advice.

Disclaimer: This tool is for education only. Results are estimates. For personalised advice, consider speaking with a healthcare provider.

Related Calculators

After calculating your BMR, use our TDEE calculator to get your total daily energy expenditure and plan your diet. You may also find our calorie calculator, calorie deficit calculator, and BMI calculator useful for weight and diet planning.

Frequently asked questions

BMR (basal metabolic rate) is the minimum calories your body needs at rest to maintain life functions (breathing, circulation, etc.). Our BMR calculator uses the Mifflin-St Jeor formula.

Enter your sex, age, height, and weight in the form above and click Calculate BMR. The calculator uses the Mifflin-St Jeor equation.

Mifflin-St Jeor: Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161.

BMR and resting metabolic rate (RMR) are very similar; both measure calories at rest. This calculator gives a BMR estimate suitable for most uses.

Mifflin-St Jeor is one of the most accurate formulas for most adults; accuracy is typically around 90–95%. For personalised values, professional testing is needed.

BMR is calories at rest. TDEE (total daily energy expenditure) includes BMR plus all activity. For diet planning, use a TDEE calculator.

BMR is the starting point; to lose weight you need to eat below your TDEE. Use our TDEE calculator, then plan a calorie deficit.

Recalculate when your weight changes significantly (e.g. 5 kg), when activity level changes, or every 3–6 months.

The same formula is used; only the constant differs (men +5, women −161). This calculator works for both.

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Content quality

Written by DietaBest Editorial Team

Medically reviewed by Dr. Alex Novak, MD (Internal Medicine)

Last updated:

This guide is for general education only and does not replace personal medical advice. Always talk to your doctor or a registered dietitian before making major diet or lifestyle changes, especially if you have a medical condition or take medication.