BMR calculator
Your calories at rest (Mifflin-St Jeor) and needs by activity level.
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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.
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Sex, age, weight, height — the formulas’ four variables.
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Compare the two formulas
Mifflin-St Jeor (current reference) and revised Harris-Benedict.
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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.