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Health & Fitness · Body Metrics Formula verified

BMR Calculator

Work out your Basal Metabolic Rate — the calories your body burns at rest — plus your estimated total daily calorie needs at five activity levels.

Details
years
155090
cm
100160220
kg
30105180
On-screen number pad
Tap to type into the highlighted field
Basal metabolic rate
1,780
Mifflin-St Jeor kcal/day
Moderate activity (TDEE)
$0
calories/day to maintain weight
Activity level Calories/day (TDEE)

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This is a population-formula estimate, not a measurement. Mifflin-St Jeor and Harris-Benedict are statistical formulas derived from population averages; an individual's actual metabolic rate can differ meaningfully due to muscle mass, medical conditions, medications and other factors a formula cannot see. It is not a substitute for indirect calorimetry or medical/nutritional advice. Consult a doctor or registered dietitian before making significant changes to your diet based on this estimate.
Visual breakdown

Daily calories by activity level

Each bar is your BMR scaled by that activity level's multiplier. BMR itself doesn't change — only how much on top of it your day-to-day movement burns.

How BMR and TDEE are calculated

Basal Metabolic Rate is the energy your body burns at complete rest — the minimum needed to keep your organs, cells and basic functions running. It's estimated here from weight, height, age and sex using the Mifflin-St Jeor equation by default, a formula the Academy of Nutrition and Dietetics identifies as the most accurate for most adults. The older Harris-Benedict equation, revised in 1984, is offered alongside it for comparison — it tends to estimate slightly higher.

Total Daily Energy Expenditure scales BMR up by an activity multiplier to estimate actual daily calorie burn, since almost nobody spends the whole day at complete rest.

BMR vs. TDEE
BMR is calories at rest. TDEE is BMR plus activity — always higher, and the more useful number for planning how much to eat.
A formula, not a measurement
Both formulas are statistical averages from population studies. Muscle mass, medical conditions and other individual factors can shift your actual BMR from the estimate.

The formulas

Mifflin-St Jeor (men): BMR = 10×kg + 6.25×cm − 5×age + 5

Women: BMR = 10×kg + 6.25×cm − 5×age − 161

Worked example

A 30-year-old man weighing 80 kg at 180 cm: BMR = 10×80 + 6.25×180 − 5×30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day. At a moderately active lifestyle (×1.55), that's a TDEE of roughly 2,759 calories/day to maintain weight.

Frequently asked questions

What is BMR and how is it different from TDEE?
BMR is the energy your body burns at complete rest just to keep essential functions running. TDEE is BMR plus the calories burned through daily activity and exercise — TDEE is always higher than BMR, and is the more useful number for planning calorie intake.
Which formula is more accurate, Mifflin-St Jeor or Harris-Benedict?
The Academy of Nutrition and Dietetics identifies the Mifflin-St Jeor equation (1990) as the most accurate predictive formula for most adults, and it's the default here. The Harris-Benedict equation (1919, revised 1984) is older and tends to run slightly higher; it's included for comparison since it's still widely referenced.
Why do these formulas only use weight, height, age and sex?
Because they're population-derived statistical formulas, not individual measurements — they estimate BMR from the variables that correlate most strongly with it across large study populations. They can't see body composition directly, so two people with identical weight, height, age and sex but very different muscle-to-fat ratios will get the same formula estimate despite likely having different actual BMRs.
How should I use my TDEE number?
TDEE is a starting estimate for calorie planning: eating close to your TDEE tends to maintain weight, a sustained deficit below it tends to produce weight loss, and a sustained surplus above it tends to produce weight gain. Because the underlying BMR is itself an estimate, treat TDEE as a starting point to adjust from based on your own results over a few weeks, not an exact target.
Sources and method
  • Mifflin-St Jeor equation — Mifflin MD, St Jeor ST, et al., "A new predictive equation for resting energy expenditure in healthy individuals," American Journal of Clinical Nutrition, 1990; identified by the Academy of Nutrition and Dietetics as the most accurate formula for most adults.
  • Harris-Benedict equation — Harris JA, Benedict FG, 1919; revised by Roza AM, Shizgal HM, "The Harris Benedict equation reevaluated," American Journal of Clinical Nutrition, 1984.
  • Activity-level multipliers for TDEE — standard published Harris-Benedict activity scale, widely used in clinical and dietetic practice.
Last reviewed: 19 Sep 2026 Sources last verified: 19 Sep 2026 Results use the assumptions explained on this page. Report an error How we check calculations

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