BMR Calculator
Calculate your Basal Metabolic Rate and daily needs.
How to Use BMR Calculator
- 1Enter gender, age, weight, and height
- 2Choose metric or imperial units
- 3Select your activity level
- 4See your BMR and TDEE for each activity level
About BMR Calculator
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain essential functions like breathing, circulation, and cell repair. The BMR Calculator uses two scientifically validated formulas — Mifflin-St Jeor and Harris-Benedict — to estimate your BMR from gender, age, weight, and height.
Once your BMR is calculated, the tool adjusts it by an activity multiplier to give your Total Daily Energy Expenditure (TDEE) — the total calories your body needs each day based on how active you are. TDEE is the baseline for setting calorie goals for weight loss, maintenance, or muscle gain.
All calculations run locally in your browser with no data sent to any server. Your physical measurements are never stored or transmitted, ensuring complete privacy for sensitive health information.
Key Features of BMR Calculator
- Calculates BMR using both Mifflin-St Jeor and Harris-Benedict formulas
- Adjusts BMR for 5 activity levels to give TDEE
- Supports both metric (kg, cm) and imperial (lb, ft/in) units
- Separate results for male and female biological profiles
- Displays all activity level TDEEs simultaneously for comparison
- Instant results as you change any input
- Useful for setting calorie targets for weight loss, maintenance, or gain
- No personal data stored or transmitted
Examples
BMR and TDEE for an active male
Calculate daily calorie needs for a moderately active 30-year-old male.
Input
Male, 30 years, 80 kg, 180 cm, Moderately active
Output
BMR: ~1,897 kcal | TDEE: ~2,941 kcal (Mifflin-St Jeor)
BMR for a sedentary female
Estimate base calorie needs for a 40-year-old sedentary female.
Input
Female, 40 years, 65 kg, 165 cm, Sedentary
Output
BMR: ~1,408 kcal | TDEE: ~1,690 kcal
Common Use Cases
- Setting a daily calorie target for a weight loss or gain plan
- Determining maintenance calories before starting a diet
- Comparing BMR formulas to understand the range of estimates
- Adjusting calorie intake when changing activity levels
- Providing a metabolic baseline for sports nutrition planning
- Understanding how age and body composition affect calorie needs
Troubleshooting
Using TDEE as a target without accounting for a deficit or surplus
Solution
TDEE is your maintenance calorie level. To lose weight, eat below TDEE; to gain weight, eat above TDEE. A common starting deficit is 500 kcal/day for approximately 0.5 kg/week loss.
Overestimating activity level
Solution
Many people overestimate how active they are. Use "Sedentary" for desk jobs with no formal exercise, "Lightly active" for 1-3 days/week of exercise, and so on.
Expecting perfect accuracy from any BMR formula
Solution
BMR formulas are statistical estimates based on population averages. Individual metabolic rate can vary by 10-20%. Use the result as a starting point and adjust based on real-world results.
Frequently Asked Questions
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body burns at rest to maintain vital functions: breathing, circulation, temperature regulation, and cell production.
What is TDEE?
TDEE (Total Daily Energy Expenditure) is your total daily calorie burn including physical activity. It is calculated by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active).
Which BMR formula is more accurate?
Mifflin-St Jeor is generally considered more accurate for most modern adults. Harris-Benedict (the original 1919 formula) tends to slightly overestimate BMR. Most dietitians now use Mifflin-St Jeor as the default.
How do I use BMR for weight loss?
Find your TDEE for your activity level. To lose weight, consume fewer calories than your TDEE — typically 300-500 kcal/day less for a steady loss of 0.3-0.5 kg per week.
Does BMR change with age?
Yes. BMR generally decreases with age as muscle mass naturally declines. This is why older individuals typically need fewer calories than younger people at the same body weight.
Does muscle mass affect BMR?
Yes. Muscle tissue burns more calories at rest than fat tissue. Individuals with more muscle mass have a higher BMR, which is one reason strength training supports long-term weight management.
Can I use this for children?
The Mifflin-St Jeor and Harris-Benedict formulas were developed for adults. For children and adolescents, specialized pediatric formulas are more appropriate.
Is my health data private?
Yes. All calculations run entirely in your browser. Your weight, height, and age are never transmitted to or stored on any server.