BMR Calculator
Calculate calories your body burns at rest
What is it?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to maintain basic functions like breathing, circulation, and cell production. It's the foundation for estimating your total daily calorie needs.
Formula
Men: BMR = 88.36 + (13.4 × weight in kg) + (4.8 × height in cm) − (5.7 × age)
Women: BMR = 447.6 + (9.2 × weight in kg) + (3.1 × height in cm) − (4.3 × age)
Based on the Revised Harris-Benedict Equation.
Formula Explanation
The equation weighs your body weight and height positively (more mass and height generally mean more calories burned at rest) and subtracts a factor for age, since metabolism tends to slow gradually over the years. Separate constants for men and women account for typical differences in muscle mass and body composition between the sexes.
Example Calculation
A 30-year-old man weighing 75 kg and 178 cm tall has a BMR of 88.36 + (13.4 × 75) + (4.8 × 178) − (5.7 × 30) ≈ 1,743 kcal/day — the calories his body burns at complete rest.
How to Use
- Select your gender.
- Enter your age, height, and weight.
- Click Calculate BMR.
- View your estimated resting calorie burn.
Benefits
- Gives a science-based starting point for setting daily calorie targets.
- Helps you understand how much of your calorie burn happens without any activity at all.
- Useful baseline before calculating TDEE for weight loss, maintenance, or gain plans.
Use Cases
- Setting a calorie floor you should rarely eat below for sustainable weight management.
- Feeding into a TDEE calculation once an activity multiplier is added.
- Tracking how BMR shifts over time with age, weight, or muscle gain.
What Your Result Means
Your BMR is the number of calories your body needs just to stay alive at complete rest — before any walking, exercise, or daily activity is added. It is not your total daily calorie need; for that, use a TDEE calculator that applies an activity multiplier to this number.
Tips
- Recalculate every few months, especially after meaningful weight or muscle changes.
- Use BMR as a floor, not a target — eating consistently below it is not recommended.
- Pair BMR with an activity multiplier (TDEE) for realistic daily calorie planning.
Common Mistakes
- Confusing BMR with TDEE and eating only at BMR level, which ignores daily activity.
- Entering height or weight in the wrong unit without switching the selector.
- Treating BMR as a fixed number instead of recalculating after major body changes.
FAQs
What's the difference between BMR and TDEE?
BMR is calories burned at complete rest, while TDEE (Total Daily Energy Expenditure) adds your activity level on top of BMR to estimate total daily calorie needs.
Can I lose weight by eating at my BMR?
Eating below your BMR for extended periods isn't recommended, since it can slow metabolism and isn't sustainable — most weight loss plans target a moderate deficit from TDEE instead.
Does BMR change over time?
Yes, BMR generally decreases with age and can change with shifts in muscle mass, so it's worth recalculating periodically.
Why do men and women have different BMR formulas?
Men typically carry more muscle mass than women at the same weight, and muscle burns more calories at rest than fat, so the equations use different constants to reflect this.
Does muscle mass affect BMR?
Yes — muscle tissue burns more calories at rest than fat tissue, so people with more muscle mass generally have a higher BMR even at the same body weight.
Is the Harris-Benedict equation the most accurate method?
It is one of the most widely used estimation methods and reasonably accurate for most people, though methods like the Mifflin-St Jeor equation or indirect calorimetry can be more precise for specific populations.
Why is my BMR lower than a friend of the same weight?
BMR depends on age, height, gender, and body composition, not just weight — differences in muscle mass or age can lead to different BMR values even at the same weight.
Should I use my BMR to plan meals?
Use TDEE (BMR plus activity) rather than BMR alone for meal planning, since BMR only reflects resting calorie burn, not your full daily needs.
References
Educational tool only, not medical advice.
Last updated: July 25, 2026