BMR Calculator
Estimate your basal metabolic rate (BMR) with the Mifflin–St Jeor equation. Enter your measurements in metric or imperial units and see an explained resting-energy estimate.
Calculate Your BMR
For adults aged 18 and older. Choose the units you prefer.
Your measurements
The calculation runs in your browser. It is an educational estimate, not a prescribed calorie target.
Your resting energy estimate
Enter your age, measurements and equation selection, then calculate to see your estimated BMR and formula.
Total daily energy expenditure also accounts for activity and other energy costs. BMR alone is not a recommended daily food intake.
What Is Basal Metabolic Rate?
Basal metabolic rate (BMR) estimates the energy your body uses to maintain essential functions at rest, including breathing, circulation and temperature regulation. It is typically expressed in kilocalories per day (kcal/day). A calculated BMR is an estimate, not a direct measurement.
Select metric or imperial measurements.
Provide age, weight, height and the equation constant.
See the daily estimate and worked formula.
Mifflin–St Jeor Formula
Male equation: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5.
Female equation: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161.
The male and female options represent the two constants in this published equation. They do not capture all biological variation and may not be appropriate for everyone.
Worked Example
For a 30-year-old using the male equation constant, weighing 70 kg and measuring 175 cm: (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 1,648.75 kcal/day, displayed as approximately 1,649 kcal/day.
BMR vs TDEE: What’s the Difference?
BMR represents estimated resting energy requirements. Total daily energy expenditure (TDEE) includes additional energy associated with movement, exercise, food digestion and other daily activities. Therefore, BMR should not be interpreted as the amount you should eat each day.
To explore a broader estimate of daily energy needs, use the TDEE Calculator. For a weight-and-height screening measure, see the BMI Calculator.
Why Your Actual Energy Use May Differ
Body composition, individual physiology, age, medical conditions and measurement differences can influence resting energy use. Predictive equations are useful for general estimates but cannot replace individualized assessment when accuracy is important.
Frequently Asked Questions
Is the ToolZippy BMR Calculator free?
Yes. The calculator can be used without creating an account.
What does kcal/day mean?
It means kilocalories per day, a common unit for estimating daily energy expenditure.
Is BMR the same as calories I should eat?
No. BMR estimates resting energy use and excludes much of your daily activity expenditure.
Can I calculate BMR in pounds and feet?
Yes. Select Imperial and enter pounds, feet and additional inches. The tool converts these measurements before applying the equation.
Is this suitable for children?
No. This version is intended for adults aged 18 or older; pediatric assessment requires age-appropriate methods.
Is the result medically exact?
No. It is a predictive estimate. Measured resting metabolic rate can differ from equation-based estimates.