BMR Calculator (Basal Metabolic Rate)
Find your Basal Metabolic Rate — the energy your body burns at complete rest — from two trusted formulas.
How to use the bmr calculator
- Enter your age, sex, height and weight.
- Click Calculate.
- Multiply BMR by an activity factor, or use the TDEE calculator, for daily needs.
Why BMR matters for nutrition
BMR is the foundation of any calorie target. Knowing it tells you the minimum your body needs and anchors your maintenance, cut and bulk calorie levels.
Why BMR is the foundation of your calorie needs
Basal Metabolic Rate is the energy your body uses just to stay alive at rest, keeping your heart, brain, and organs running. It typically accounts for 60-70% of total daily energy use, which makes it the single largest component of your calorie needs and the base on which TDEE is built.
What changes your BMR
Lean body mass is the biggest driver, which is why building muscle modestly raises BMR. Age, sex, and body size also matter, and very aggressive dieting can lower BMR temporarily as the body adapts. You cannot dramatically 'boost' metabolism, but preserving muscle through resistance training and adequate protein keeps it as high as possible.
The two formulas compared across real profiles
| Profile | Mifflin-St Jeor | Harris-Benedict | Gap |
|---|---|---|---|
| Woman, 30, 165 cm, 60 kg | 1,320 kcal | 1,384 kcal | +64 |
| Woman, 45, 170 cm, 70 kg | 1,377 kcal | 1,427 kcal | +50 |
| Man, 30, 180 cm, 80 kg | 1,780 kcal | 1,854 kcal | +74 |
| Man, 45, 175 cm, 90 kg | 1,774 kcal | 1,878 kcal | +104 |
| Man, 60, 175 cm, 85 kg | 1,649 kcal | 1,726 kcal | +77 |
Harris-Benedict reads consistently higher, usually by 50-100 kcal, and the gap widens with body weight. That is why Mifflin-St Jeor became the modern default: the older equation was derived from a smaller, less representative sample and tends to overestimate resting needs.
Frequently asked questions
Which BMR formula should I trust?
Mifflin-St Jeor is generally the most accurate for modern populations. Harris-Benedict is shown for comparison.
What is the difference between BMR and TDEE?
BMR is your resting energy need; TDEE adds the calories from digestion, daily movement, and exercise on top. TDEE is what you actually burn in a normal day.
Can I increase my BMR?
Modestly, mainly by building and retaining muscle. Crash diets can lower it, so eating enough protein and lifting weights helps protect it.
Which BMR formula is most accurate?
Mifflin-St Jeor is the most accurate for most people. The Harris-Benedict equation is an older alternative that tends to read slightly higher.
Related tools
TDEE Calculator
Calculate the calories you burn per day (your TDEE) to set targets for cutting, maintaining, or bulking.
Macro Calculator
Turn your calorie target into daily protein, carbohydrate, and fat goals based on your objective.
Calorie Deficit Calculator
Turn a goal weight and timeframe into the daily calories and deficit you need to hit it.