BMR calculator
Your calories at rest (Mifflin-St Jeor) and needs by activity level.
- Instant
- Free
- Private (processed locally)
- No sign-up
Your body’s energy budget, line by line
Before talking deficit or bulking, you need the starting point: how much your body burns doing nothing. The tool computes your basal metabolic rate with both reference formulas, then converts it into real daily needs (TDEE) across five activity levels.
-
Fill in your profile
Sex, age, weight, height : the formulas’ four variables.
-
Compare the two formulas
Mifflin-St Jeor (current reference) and revised Harris-Benedict.
-
Read your TDEE
The table converts to daily calories based on your activity.
Example: man, 35, 75 kg, 175 cm
| Indicator | Value |
|---|---|
| BMR Mifflin-St Jeor | 1,674 kcal |
| BMR Harris-Benedict | 1,734 kcal |
| TDEE sedentary (×1.2) | 2,009 kcal |
| TDEE moderately active (×1.55) | 2,594 kcal |
These formulas estimate a statistical average within ±10%: genetics, body composition and thyroid make the real value vary. For a personalised nutrition plan, see a dietitian or doctor.
Frequently asked questions
What exactly is the basal metabolic rate?
The energy your body uses for vital functions, breathing, circulation, temperature, brain, lying down, fasted, motionless. It is 60 to 70% of your total expenditure: your biggest energy budget item is not sport, it is existing.
Mifflin-St Jeor or Harris-Benedict: which to trust?
Mifflin-St Jeor (1990) is the current reference, recommended by the Academy of Nutrition and Dietetics: it was calibrated on modern populations. Harris-Benedict (1919, revised 1984) slightly overestimates. The gap between the two shows the uncertainty margin.
How do I go from BMR to daily calories?
Multiply by your activity level (the TDEE method): ×1.2 sedentary, ×1.375 lightly active (1-3 sessions/week), ×1.55 moderately active (3-5), ×1.725 very active (6-7), ×1.9 extremely active (physical job + sport). The tool’s table does the maths.
Why does my metabolism drop with age?
The formulas subtract about 5 kcal (Mifflin) per year: muscle mass naturally declines and cellular metabolism slows. Good news: strength training partly compensates, each kilo of muscle burns about 13 kcal/day at rest, versus 4.5 for fat.