BMR / Calorie Calculator
Daily calories burned at rest (Mifflin-St Jeor).
Input sheet
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Basal metabolic rate is the energy your body burns just to stay alive at rest — breathing, circulating blood, keeping warm. It's the foundation every calorie target is built on, since your daily needs are BMR scaled up by how much you move.
How it works
Mifflin-St Jeor equation. Multiply BMR by an activity factor (1.2 sedentary to 1.7 very active) for total daily calories.
This uses the Mifflin-St Jeor equation, the formula most dietitians consider the most accurate for the general population. It factors in weight, height, age, and sex, since each shifts how much energy you burn at baseline.
BMR alone isn't your eating target. Multiply it by an activity factor — roughly 1.2 if sedentary, up to about 1.725 if very active — to get total daily calories. The tool shows a couple of those multiples so you can see the range.
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (men) or − 161 (women). Total calories = BMR × activity factor.
Worked examples
A 30-year-old man, 5'10" (177.8 cm), 175 lb (79.4 kg). → BMR about 1,760 cal/day; roughly 2,420 cal lightly active.
10 × 79.4 + 6.25 × 177.8 − 5 × 30 + 5 ≈ 1,760; × 1.375 ≈ 2,420.
A 40-year-old woman, 5'6" (167.6 cm), 150 lb (68.0 kg). → BMR about 1,367 cal/day.
10 × 68.0 + 6.25 × 167.6 − 5 × 40 − 161 ≈ 1,367.
Tips & gotchas
- Pick your activity factor honestly — most people overestimate, which is why their 'maintenance' calories don't hold.
- Use BMR-based targets as a starting point, then adjust by what the scale actually does over two to three weeks.
- BMR falls with age and with weight loss, so recalculate after a significant change rather than reusing an old number.
- Crash diets that drop you below BMR for long stretches tend to backfire through muscle loss and metabolic slowdown.
FAQ
What's the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE (total daily energy expenditure) is BMR multiplied by your activity factor — it's the number you actually eat against.
Why does the formula change for men and women?
Men typically carry more lean muscle, which burns more energy at rest. The +5 versus −161 constant accounts for that average difference in body composition.
Should I ever eat below my BMR?
Briefly and modestly it can be fine, but sustained eating well under BMR risks muscle loss and adaptation. Most plans create the deficit by raising activity rather than slashing intake that low.
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