BMR Calculator

Calculate your Basal Metabolic Rate (BMR) and daily calorie needs based on your activity level.

US UnitsMetric Units

Age (years)

Weight (lbs)

Sex

MaleFemale

Height (ft)

Height (in)

Activity Level

Goal

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This BMR calculator is for informational purposes only. It provides estimates based on published equations. It is intended for non-pregnant, non-breastfeeding adults. For personalized nutrition or medical advice, consult a qualified healthcare professional.

How to Use the BMR Calculator
What is BMR?
BMR Formulas
Activity Level Explained
What Affects BMR?
Frequently Asked Questions
References

How to Use the BMR Calculator

Select your preferred unit system: US (feet/inches and pounds) or Metric (centimeters and kilograms).
Enter your age in years (18–80) and select your sex. For adults 18 and older.
Enter your height and weight in the input fields.
Open Settings to choose a BMR formula. Mifflin-St Jeor is recommended for most people.
Click Calculate to see your BMR and estimated daily calorie needs at six activity levels.
Use the Try buttons for quick examples, or the copy and share buttons to save or send your result.

What is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, life-sustaining functions while at rest. These include breathing, circulation, nutrient processing, and cell production.

Resting metabolism is typically the largest component of total daily energy expenditure, but its contribution varies between individuals based on age, gender, body size, body composition, and activity level. Understanding your BMR is the first step in planning an effective nutrition or fitness strategy.

BMR is often confused with Resting Metabolic Rate (RMR). While similar, BMR is measured under stricter conditions, whereas RMR is more practical and commonly used in everyday calculations.

BMR Formulas

Mifflin-St Jeor Equation

Considered the most accurate formula for the general population.

Male

Men: BMR = 10W + 6.25H − 5A + 5

Female

Women: BMR = 10W + 6.25H − 5A − 161

Revised Harris-Benedict Equation

An update to the original 1919 equation, revised in 1984 for improved accuracy.

Male

Men: BMR = 13.397W + 4.799H − 5.677A + 88.362

Female

Women: BMR = 9.247W + 3.098H − 4.330A + 447.593

Katch-McArdle Formula

Uses lean body mass instead of total body weight. Requires an estimate of body fat percentage.

BMR = 370 + 21.6 × Lean Body Mass (kg)

Where: W = weight in kg, H = height in cm, A = age in years

Activity Level Explained

Activity Level	Multiplier	Description
Sedentary	1.2	Little or no exercise, desk job
Lightly Active	1.375	Light exercise 1–3 days/week
Moderately Active	1.55	Moderate exercise 3–5 days/week
Very Active	1.725	Hard exercise 6–7 days/week
Extra Active	1.9	Intense exercise daily or physical job

What Affects BMR?

Several factors influence your basal metabolic rate beyond what the equations capture.

•Muscle mass: More muscle raises BMR because muscle tissue burns more calories at rest than fat.
•Age: BMR declines with age as muscle mass typically decreases and fat increases.
•Genetics: Hereditary traits can cause metabolic differences between individuals.
•Environment: Cold or hot environments can temporarily raise BMR as the body works to regulate temperature.
•Diet: Prolonged calorie restriction can significantly lower BMR as the body adapts to lower energy intake.
•Pregnancy: Supporting a growing fetus increases metabolic demands and BMR.
•Substances: Caffeine and some other compounds can temporarily increase energy expenditure, but effects vary between individuals.

Frequently Asked Questions

What is a normal BMR?

There is no single "normal" BMR. It varies widely by age, sex, height, and weight. For adult men, typical BMR ranges from 1,400 to 1,800 calories/day. For adult women, it ranges from 1,200 to 1,500 calories/day.

Does muscle increase BMR?

Yes. Muscle tissue is more metabolically active than fat tissue. Building muscle through resistance training can increase your BMR over time, meaning you burn more calories even at rest.

How accurate is BMR?

BMR equations are estimates. Studies show a 26% natural variance between individuals even when controlling for all known factors. For precise measurement, consult a specialist or use indirect calorimetry.

Should I eat my BMR calories to lose weight?

BMR is the minimum your body needs at rest. Eating exactly your BMR without activity would be a very low-calorie diet. Most people need BMR × activity factor for maintenance. For weight loss, a moderate deficit of ~500 calories/day below maintenance is recommended for about 1 lb/week loss. Use the Goal selector to calculate your target calories.

How often should I recalculate my BMR?

Recalculate whenever your weight changes significantly (5+ lbs), or at least every 3–6 months. Age-related changes are gradual, but weight changes have an immediate effect on BMR.

How do I calculate calories for weight loss or gain?

Select a Goal: Maintain keeps your BMR as-is. Lose creates a calorie deficit (0.5-2 lb/week). Gain creates a surplus. A 500 cal/day deficit ≈ 1 lb/week weight loss. A 500 cal/day surplus ≈ 1 lb/week weight gain. The calculator shows your target calories and the daily deficit/surplus needed.

What is the difference between BMR and TDEE?

BMR estimates the energy your body uses at rest to maintain basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) estimates your total daily energy use after accounting for physical activity and other components. TDEE is calculated by multiplying your BMR by an activity factor, and it represents the calories you actually need each day.