BMR Calculator

Estimate your basal metabolic rate — the calories your body burns at complete rest — using three well-known formulas, and see how many calories you need at different activity levels.

Units
Sex
Basal metabolic rate
1,333 calories/day
Mifflin-St Jeor
1,333 cal
Revised Harris-Benedict
1,395 cal
Katch-McArdle
1,362 cal
Activity levelCalories/day
Sedentary1,600
Lightly active1,833
Moderately active2,066
Very active2,300
Extra active2,533

The table multiplies your BMR by standard activity factors (1.2–1.9) to estimate total daily energy expenditure.

What is BMR?

Your basal metabolic rate (BMR) is the number of calories your body needs to stay alive at complete rest — to breathe, circulate blood, regulate temperature and keep your organs working. For most people BMR accounts for about 60–70% of the calories they burn each day. The rest comes from digesting food and physical activity.

How to use the BMR calculator

  1. Choose your units and enter your sex, age, height and weight.
  2. Pick a formula. Mifflin-St Jeor is the best default; use Katch-McArdle if you know your body fat percentage.
  3. See your BMR, a comparison of the formulas, and estimated daily calories for each activity level.

BMR formulas

Mifflin-St Jeor (1990)

Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

Revised Harris-Benedict (Roza & Shizgal, 1984)

Men: 13.397 × weight + 4.799 × height − 5.677 × age + 88.362 Women: 9.247 × weight + 3.098 × height − 4.330 × age + 447.593

Katch-McArdle

BMR = 370 + 21.6 × lean body mass (kg) Lean body mass = weight × (1 − body fat %)

Katch-McArdle uses lean mass instead of sex and age, so it can be more accurate for lean, muscular people — as long as your body fat estimate is accurate.

Example

A 30-year-old woman who is 165 cm (5 ft 5 in) tall and weighs 60 kg (about 132 lb) has a Mifflin-St Jeor BMR of 10 × 60 + 6.25 × 165 − 5 × 30 − 161 = 1,320 calories per day. The revised Harris-Benedict equation gives about 1,384 calories. If she is moderately active, her total daily needs are roughly 1,320 × 1.55 ≈ 2,046 calories.

What affects your BMR?

  • Muscle mass: muscle burns more energy at rest than fat, so more muscle means a higher BMR.
  • Age: BMR tends to decline with age, partly due to muscle loss.
  • Body size: larger bodies need more energy.
  • Sex: men usually have higher BMRs because of greater lean mass.
  • Genetics, hormones and health: thyroid function, for example, has a strong effect on metabolism.

Strength training is one of the most effective ways to maintain or increase your BMR over time.

Frequently asked questions

What is a normal BMR?

Most adult women have a BMR of roughly 1,200–1,500 calories per day and most adult men roughly 1,500–1,900, though it varies with size, age and muscle mass.

What is the difference between BMR and TDEE?

BMR is the energy you burn at complete rest. TDEE (total daily energy expenditure) adds the calories burned through digestion and physical activity. TDEE is what you use to plan your daily calorie intake.

Which BMR formula is most accurate?

For most healthy adults, the Mifflin-St Jeor equation is considered the most accurate of the common formulas. Katch-McArdle can be better for lean, muscular people if body fat is measured accurately.

Should I eat below my BMR to lose weight?

Generally no. Eating below your BMR for long periods can lead to muscle loss, fatigue and nutrient deficiencies. A moderate deficit below your TDEE is a safer approach.

How can I increase my BMR?

Building muscle through strength training is the most reliable way. Staying active, eating enough protein and getting adequate sleep also support a healthy metabolism.

This calculator provides general information only and is not a substitute for professional medical advice, diagnosis or treatment. Always consult a doctor or other qualified health provider about your individual situation.

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