BMR Calculator
Calculate Basal Metabolic Rate using Mifflin-St Jeor equation.
Input & results
Input values
Results
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Calculation History
- Your calculations will appear here.
Recent calculations are saved automatically as you adjust inputs.
Health and fitness results are estimates for general informational purposes only and are not medical advice. Consult a qualified healthcare professional before making health decisions. See our full disclaimer.
What is BMR?
A BMR (Basal Metabolic Rate) Calculator estimates the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, and cell production.
Your BMR is the energy your body needs just to stay alive, before any activity. This calculator uses the widely accepted Mifflin-St Jeor equation, which factors in weight, height, age, and sex to estimate daily resting calories. BMR forms the foundation for calculating total daily energy expenditure (TDEE) and planning calorie targets for weight loss, maintenance, or gain.
Why is it used?
Knowing your BMR is the starting point for any nutrition plan. It tells you the minimum calories your body requires, so you can set realistic intake targets and avoid eating too little or too much when pursuing a fitness goal.
Who should use it?
Anyone planning weight loss, maintenance, or muscle gain, and people who want to understand their metabolism before setting calorie goals.
How it works
- Enter Weight (kg), Height (cm), Age (years), Gender in the input fields.
- The calculator validates your entries and applies the correct bmr formula.
- Results update in real time as you change any value — no submit button needed.
- Review the formula, variable definitions, and worked example below to see how the answer is derived.
Formula
Variable definitions
| Variable | Meaning |
|---|---|
| W | Weight in kilograms |
| H | Height in centimeters |
| A | Age in years |
| s | Sex constant: +5 for men, −161 for women |
How the formula works
- Multiply weight in kg by 10.
- Add 6.25 times height in cm.
- Subtract 5 times age in years.
- Add 5 for men or subtract 161 for women.
Example calculation
BMR for a 30-year-old man, 75 kg, 178 cm.
| Input | Value |
|---|---|
| Sex | Male |
| Weight | 75 kg |
| Height | 178 cm |
| Age | 30 |
- 10 × 75 = 750
- 6.25 × 178 = 1112.5
- 5 × 30 = 150
- BMR = 750 + 1112.5 − 150 + 5 = 1717.5
Result
More examples
30-year-old woman, 62 kg, 165 cm.
| Input | Value |
|---|---|
| Sex | Female |
| Weight | 62 kg |
| Height | 165 cm |
| Age | 30 |
- BMR = 620 + 1031.25 − 150 − 161
Result
Methodology
- Gather Weight (kg), Height (cm), Age (years), Gender from your documents or estimates.
- Enter each value in the matching field; units must match the labels.
- The calculator applies the BMR formula and updates results in real time.
- Compare scenarios by changing one input at a time.
Benefits
- Establish your baseline calorie needs.
- Set realistic targets for loss, gain, or maintenance.
- Build a foundation for calculating TDEE.
- Avoid under- or over-eating on a fitness plan.
Use cases
- Starting a weight-loss or muscle-gain plan.
- Calculating daily calorie targets.
- Understanding how metabolism changes with age.
- Comparing BMR before and after body changes.
Tips & important notes
- BMR is calories at rest — multiply by an activity factor for TDEE.
- Muscle mass raises BMR, so strength training helps.
- BMR naturally declines with age.
- Use accurate, current measurements for the best estimate.
Common mistakes
- Confusing BMR (at rest) with total daily calorie needs.
- Entering height in inches instead of centimeters.
- Using the wrong sex constant in the formula.
Related concepts
- TDEE and activity multipliers
- Calorie deficit and surplus
- Mifflin-St Jeor vs Harris-Benedict equations
Good to know