Estimate your Basal Metabolic Rate — calories burned at complete rest — using the Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle formula. See daily calorie targets across five activity levels.
Results update live as you type.
Your Basal Metabolic Rate
Sedentary
1,980
Light
2,269
Moderate
2,558
Heavy
2,846
Athlete
3,135
| Activity level | Multiplier | Daily calories | Above BMR |
|---|
The Formula
Your Basal Metabolic Rate is the energy your body burns at total rest — keeping the heart beating, lungs breathing, organs running, and temperature stable. It's typically 60–70% of your daily calorie burn.
We default to Mifflin-St Jeor, the most accurate equation for most adults. To estimate your full daily calorie needs, we multiply BMR by activity multipliers from 1.2 (sedentary) to 1.9 (athlete).
BMR Equations
About This Tool
A BMR calculator estimates the minimum calories your body needs to function at complete rest — what you'd burn lying still all day, with no activity, no exercise, no digestion. It's the foundation number behind any serious calorie or weight-management plan.
The most accurate equation for the general population is Mifflin-St Jeor (1990), which improved on the older Harris-Benedict formula by reflecting modern body compositions more accurately. If you know your body-fat percentage, Katch-McArdle usually wins because it works from lean body mass, which is what actually burns the calories.
Once you have BMR, multiply it by an activity factor (1.2–1.9) to estimate your Total Daily Energy Expenditure (TDEE). Eat at TDEE to maintain weight; subtract 15–25% to lose fat; add 10–20% to build muscle.
Instant Live Results
BMR updates the moment you change a value.
Three Formulas
Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle in one place.
5 Activity Levels
Sedentary to athlete — see daily totals across the board.
100% Free & Private
No account needed. All maths runs in your browser.
Imperial & Metric
Switch between ft/lbs and cm/kg instantly.
Visual Breakdown
See BMR vs. activity calories at a glance.
Five simple inputs unlock your daily calorie blueprint.
Choose Imperial (ft/in, lbs) or Metric (cm, kg). The fields swap to match.
Sex changes a constant in the equation. Age matters too — BMR declines slowly with age.
Use morning weight after using the bathroom for the most stable reading.
Stick with Mifflin-St Jeor unless you know your body-fat % — then use Katch-McArdle.
Pick the activity level that matches your week — that's your maintenance calories.
Subtract 15–25% for fat loss, add 10–20% for muscle gain. Reassess every 2–4 weeks.
Everything you need to know about Basal Metabolic Rate.
For most adults, Mifflin-St Jeor is accurate to within ±10%. Katch-McArdle wins when you know your body-fat percentage because it works from lean body mass. Harris-Benedict is still common but tends to over-predict.
Yes — BMR typically falls 1–2% per decade after age 20, mostly driven by muscle loss. Strength training and adequate protein (1.6–2.2 g/kg) slow this decline considerably.
BMR is calories burned at total rest. TDEE is your full daily burn — BMR plus activity, exercise, and the energy cost of digesting food. The activity-level rows in this calculator give you TDEE.
Pick your activity row (that's TDEE) and subtract 15–25% to create a deficit. A 500-kcal/day cut ≈ 1 lb fat loss per week. Don't eat below BMR for long stretches — it slows metabolism and erodes muscle.
Almost. BMR is measured after 12 hours of fasting in a thermoneutral lab. RMR (resting metabolic rate) is taken under less strict conditions and runs ~10% higher. The two are used interchangeably in practice.
Men typically have more muscle and less body fat per pound than women, and muscle burns more calories at rest. The formulas use a sex constant to reflect this average difference in body composition.
Yes — the biggest lever is building muscle. Each pound of muscle burns ~6 kcal/day at rest vs. ~2 kcal/day for fat. Adequate protein, regular strength training, and decent sleep are the practical levers.