What is the BMR Calculator?
The BMR calculator estimates your Basal Metabolic Rate, the number of calories your body burns at complete rest to sustain vital functions such as breathing, circulation, cell production, and temperature regulation. BMR is the foundation of any weight management plan because it tells you the minimum energy your body needs before any activity. Nutritionists and fitness coaches use it to design calorie targets for weight loss, gain, or maintenance.
How to Use the BMR Calculator
- Enter your age in years
- Select your sex from the dropdown
- Enter your weight in kilograms and height in centimeters
- Press Calculate BMR to see your result
BMR Formula (Mifflin-St Jeor Equation)
- Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
- Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
The Mifflin-St Jeor equation is widely regarded as one of the most accurate formulas for estimating resting energy expenditure in the general population.
Example Calculation
| Field | Value |
|---|---|
| Sex | Male |
| Age | 30 years |
| Weight | 70 kg |
| Height | 175 cm |
| BMR | ≈1,686 kcal/day |
Why Calculate Your BMR?
Your BMR represents roughly 60 to 75 percent of the calories you burn every day. Knowing it helps you understand your energy needs and set realistic calorie targets. To lose weight, you consume fewer calories than your total daily energy expenditure (BMR plus activity). To gain weight, you consume more. Without a BMR estimate, diet and exercise plans are often guesswork that leads to frustration.
BMR vs. TDEE
- BMR: calories burned at complete rest
- TDEE: total daily energy expenditure, which includes BMR plus activity, exercise, and the thermic effect of food
The calculator also provides a sedentary daily calorie estimate (BMR × 1.2) as a starting point. Multiply your BMR by a higher activity factor to estimate TDEE for an active lifestyle.
How the BMR Calculator Works
The calculator applies the Mifflin-St Jeor equation using your age, sex, weight, and height. Because the formula differs for men and women, the calculator automatically selects the correct variant based on your sex selection. It then multiplies the BMR by a sedentary activity factor (1.2) to give a baseline daily calorie estimate. All processing happens locally in your browser, so your personal data is never transmitted or stored.
Frequently Asked Questions
What factors affect BMR?
Age, sex, weight, height, muscle mass, genetics, and hormone levels all influence BMR. Muscle burns more calories than fat at rest, so two people of the same weight can have different BMRs.
Is the Mifflin-St Jeor formula accurate?
It is considered one of the most accurate predictive formulas for most adults and is the current clinical standard recommended by many health organizations.
How do I use my BMR to lose weight?
Calculate your total daily energy expenditure (TDEE) and consume about 500 calories less per day to lose roughly 0.5 kg per week. Always consult a healthcare professional before starting any diet.