BMR Calculator
Estimate your basal metabolic rate with the Mifflin-St Jeor equation and see how it scales with the standard activity multipliers. For calorie targets aimed at losing or gaining weight, the Calorie Calculator builds on this same engine.
Calculate your BMR
Example: male, 70 kg, 175 cm, age 25 → 1,674 kcal/day.
The Mifflin-St Jeor equation
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + s, where s is +5 for men
and −161 for women. For a 25-year-old man at 70 kg and 175 cm: 700 + 1093.75 − 125 + 5 =
1,674 kcal/day — the example is computed by the same tested engine as the calculator.
The result also lists the standard activity multipliers (1.2 sedentary through 1.9 extra active)
so you can see realistic daily totals at a glance.
What BMR is useful for
BMR anchors every calorie plan: maintenance intake is BMR times an activity factor, and deficits or surpluses are set relative to that. It also explains why "eat less, move more" math differs between people — a taller, heavier, younger body idles at a higher burn rate, exactly as the equation's terms suggest.
Frequently asked questions
What exactly is BMR?
Basal metabolic rate is the energy your body uses for its baseline functions — breathing, circulation, cell maintenance — measured at complete rest. It typically accounts for 60–75% of total daily calories.
Why the Mifflin-St Jeor equation?
It is the equation most often recommended in modern practice, having outperformed the older Harris-Benedict formula in validation studies of contemporary populations. The formula: 10×kg + 6.25×cm − 5×age, plus 5 for men or minus 161 for women.
How accurate is the estimate?
Population equations land within about ±10% for most people, but genetics, body composition, and thyroid function all shift real metabolic rates. Only indirect calorimetry measures BMR directly.
Should I eat at my BMR?
No — BMR is a floor, not a target. You use more than that living an ordinary day. See the Calorie Calculator, which multiplies BMR by an activity factor for realistic totals.
Not medical advice: this calculator provides general educational estimates from published population formulas and cannot account for your individual health context. Consult a qualified healthcare professional before changing diet or exercise. Data is processed locally in your browser and never transmitted. See the methodology page.