BMR Calculator
Calculate your Basal Metabolic Rate (BMR) — the number of calories your body burns at rest. Then multiply by your activity level to find your Total Daily Energy Expenditure (TDEE).
BMR vs TDEE
BMR is the minimum calories needed to sustain basic life functions at complete rest.
TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor — the actual calories you burn per day including all activity.
To lose weight at a safe rate of ~1 lb/week, eat 500 calories below your TDEE. To gain muscle, eat 250–500 calories above TDEE.
Frequently Asked Questions
This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate for most people: Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161.
BMR formulas are estimates accurate to within ~10% for most people. Factors like muscle mass, genetics, and medical conditions affect actual metabolic rate. Use it as a starting point and adjust based on real-world results.
What BMR measures
Basal metabolic rate is the energy your body uses at complete rest — maintaining temperature, circulation, breathing, cell repair and brain function. It is what you would burn lying still all day without digesting anything.
For most people BMR accounts for roughly 60–70% of total daily energy expenditure, which is why it dominates the calculation even though it involves no activity at all.
The Mifflin-St Jeor equation
Developed in 1990, it is generally regarded as more accurate for contemporary populations than the older Harris-Benedict equation, which tends to overestimate.
What drives the number
- Lean mass — muscle is metabolically active; fat much less so. This is the main reason two people of identical weight can differ.
- Body size — more tissue requires more maintenance energy.
- Age — BMR declines gradually, largely through loss of lean mass rather than age itself.
- Sex — on average men carry more lean mass at the same weight.
- Genetics and thyroid function — individual variation around the predicted figure is real and can be substantial.
BMR is not your calorie target
Eating at BMR means eating as though you spent the entire day motionless. Even a sedentary person burns meaningfully more once ordinary movement and digestion are counted.
BMR is the starting input for a TDEE calculation, not an intake goal in itself.
Limits of the estimate
Any equation predicts a population average for your inputs. Individuals can sit noticeably above or below it. Treat the output as a starting point to test against real-world results over several weeks, not a measurement.
General information only — not medical or dietary advice.