BMR Calculator
Health
Basal Metabolic Rate calculator
Enter your age, sex, height, and weight to estimate the calories your body burns at rest — your metabolic baseline.
BMR Calculator
Estimated BMR
1,649 kcal/day
Weight (kg)
70
Height (cm)
175
How calculations work
BMR (Basal Metabolic Rate) is estimated with the Mifflin–St Jeor formula using weight, height, age, and sex. The result approximates the number of kilocalories needed at rest to support basic physiological functions.
How to interpret results
Treat BMR as a resting baseline. Real daily needs depend on activity, health, and environment. This number is a starting point for further planning and not a clinical measurement.
Disclaimer
What this calculator does
Basal Metabolic Rate (BMR) is the number of kilocalories your body requires each day to perform essential physiological functions — breathing, circulation, cell production, and temperature regulation — while completely at rest. This calculator uses the Mifflin–St Jeor equation, one of the most widely validated BMR formulas, to return an approximate daily calorie baseline.
Who should use this calculator
Anyone interested in understanding their resting energy needs — people planning nutrition, fitness coaches designing programmes, dietitians doing initial assessments, or curious individuals setting calorie targets. BMR is a foundational number: once you know it, you can estimate total daily needs by applying an activity multiplier with our calorie calculator.
How this calculator works
The Mifflin–St Jeor formula computes BMR as follows: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. The formula accounts for the metabolic differences between sexes and the decline in metabolic rate with age. All calculations execute locally in your browser with no external data calls.
How to interpret your result
The output is an estimate of the calories your body needs at complete rest. It does not include calories burned through daily activities or exercise. To estimate your total daily needs, multiply BMR by an activity factor: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), or very active (×1.725). Eating significantly below your BMR is generally not recommended without medical supervision.
Example
A 30-year-old man weighing 70 kg and 175 cm tall has a BMR of approximately 10×70 + 6.25×175 − 5×30 + 5 = 1,648 kcal/day. A 25-year-old woman weighing 60 kg and 165 cm tall has a BMR of about 10×60 + 6.25×165 − 5×25 − 161 = 1,370 kcal/day. Enter your values above for a personalised estimate.
Limitations & disclaimer
BMR estimates are approximate. Individual variation due to body composition, genetics, hormonal status, and health conditions can cause actual resting energy needs to differ by 10–15% from the formula output. This calculator does not replace medical or metabolic testing (such as indirect calorimetry). Consult a healthcare professional for personalised dietary advice.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the energy your body uses at complete rest — just to keep organs functioning. TDEE (Total Daily Energy Expenditure) adds the calories burned through physical activity. To get your TDEE, multiply BMR by an activity factor or use our calorie calculator.
Which formula is more accurate — Harris–Benedict or Mifflin–St Jeor?
Research published in the Journal of the American Dietetic Association found the Mifflin–St Jeor equation to be the most accurate predictor of BMR for most adults. It is the formula used by this calculator.
Does BMR decrease with age?
Yes. BMR naturally declines with age due to loss of lean muscle mass and hormonal changes. This is why the Mifflin–St Jeor formula includes age as a variable. Regular resistance training can help slow the decline.
Why does sex affect BMR?
On average, men have a higher proportion of lean muscle mass relative to body fat, which requires more energy to maintain. The formula accounts for this with a different constant for men and women.
Can I use BMR to plan a diet?
BMR tells you the minimum calories your body needs at rest. Eating below your BMR for extended periods is generally not recommended. For diet planning, use your TDEE (which includes activity) and reduce by a safe deficit of 10–20%.