BMR Calculator
Usage Tips
Check the basic energy your body uses at rest
BMR is an estimate of the basic energy your body needs for essential functions like breathing, maintaining body temperature, and blood circulation. Enter your sex, age, height, and weight to calculate daily BMR, then compare how your baseline energy use changes when your weight or body composition changes.
What is BMR Calculator?
BMR stands for Basal Metabolic Rate, the minimum energy your body uses at complete rest to support essential functions such as breathing, heartbeat, blood circulation, temperature regulation, brain activity, and organ function. This BMR calculator applies sex, age, height, and weight to the Mifflin-St Jeor equation and reports estimated resting calories in kcal/day. It supports centimeters and kilograms as well as feet, inches, and pounds for international users. The result can help you understand your baseline metabolism, but it is an estimate rather than a laboratory measurement, medical diagnosis, or personalized daily calorie prescription.
How to Use
- 1Select male or female. The Mifflin-St Jeor BMR formula uses a different final constant for each option.
- 2Enter your current age in completed years. Estimates may be less representative for children, adolescents, and some older adults.
- 3Choose a height system. Enter one value in centimeters, or enter feet and inches in their separate fields.
- 4Choose kilograms or pounds for weight and enter your current body weight. Selecting the wrong unit can change the result substantially.
- 5Select Calculate BMR. Imperial measurements are converted to metric units before the equation is applied.
- 6Read the result in kcal/day as an estimate of resting calories. Recalculate after meaningful changes in weight or body composition and use the number as general reference information.
Reference Knowledge
- ●The BMR formula for men is 10×weight (kg) + 6.25×height (cm) - 5×age + 5.
- ●The BMR formula for women is 10×weight (kg) + 6.25×height (cm) - 5×age - 161.
- ●The Mifflin-St Jeor equation is widely used to estimate resting energy requirements in modern adults.
- ●BMR and RMR are related but not identical. BMR assumes stricter complete-rest testing conditions, while RMR is measured under less restrictive resting conditions and may be slightly higher.
- ●There is no single normal or average BMR for everyone. Sex, age, height, weight, and body composition produce a wide range of healthy values.
- ●Basal metabolic rate often declines with age as lean mass and activity patterns change, although the amount varies substantially between individuals.
- ●Muscle tissue uses more energy at rest than fat tissue, so people with more lean mass may have a higher measured basal metabolic rate at the same body weight.
- ●A formula cannot directly account for body fat, muscle mass, genetics, hormones, illness, medication, sleep, or testing conditions, so calculated BMR may differ from a laboratory measurement.
FAQ
Q.What does BMR mean?
BMR means Basal Metabolic Rate. It describes the calories your body needs at complete rest for essential processes such as breathing, heartbeat, circulation, temperature regulation, and organ function.
Q.How accurate is a BMR calculator?
The Mifflin-St Jeor equation is a widely used population-based estimate, but it cannot measure individual metabolism directly. A calculated result can differ from actual energy expenditure, sometimes by several hundred calories. Indirect calorimetry performed under controlled conditions is needed for a more precise measurement.
Q.Why are the BMR formulas for men and women different?
The Mifflin-St Jeor equation uses different constants to reflect average differences in body composition and metabolism between male and female populations. The formula for men adds 5, while the formula for women subtracts 161, but individual variation extends beyond sex.
Q.What is an average BMR?
There is no universal average BMR because age, sex, height, weight, and body composition vary widely. Published averages describe specific populations and should not be treated as a personal target. Your own inputs provide a more relevant estimate.
Q.Does BMR decrease with age?
Basal metabolic rate commonly decreases as people age, especially when lean muscle mass and physical activity decline. The rate of change varies, and maintaining muscle through appropriate resistance training and nutrition can influence the trend.
Q.Can building muscle increase BMR?
Muscle tissue requires more resting energy than fat tissue, so increasing lean mass can raise measured basal metabolic rate. The change is usually gradual rather than dramatic and depends on consistent training, recovery, nutrition, and overall body composition.
Q.Can I enter height in feet and inches and weight in pounds?
Yes. Select ft/in for height and lb for weight. The calculator converts feet, inches, and pounds to centimeters and kilograms before applying the same BMR formula, so equivalent measurements produce essentially the same result.
Q.What is the difference between BMR and RMR?
BMR represents minimum energy use under strict conditions such as fasting and complete rest. Resting Metabolic Rate, or RMR, is measured under less restrictive resting conditions and is often slightly higher. The terms are sometimes used interchangeably in general fitness content.
Q.When should I recalculate my BMR?
Recalculate after a meaningful change in body weight, muscle mass, or body fat, or periodically as age and health conditions change. Use accurate current measurements and the same units when comparing results over time.
Q.Can this result be used for medical diagnosis or a diet prescription?
No. This BMR calculator provides general educational information and does not replace medical assessment or personalized nutrition advice. Consult a qualified healthcare or nutrition professional for medical conditions, pregnancy, eating concerns, or clinical meal planning.