⚡ BMR Calculator

Calculate your Basal Metabolic Rate — calories burned at complete rest. Compare Mifflin-St Jeor and Harris-Benedict formulas. BMR is the foundation; add activity separately on the TDEE page.

Basal Metabolic Rate — Calories Burned at Complete Rest

BrainyCalculators editorial insight — unique to this tool

BMR is energy to keep organs functioning lying still — Mifflin-St Jeor is most cited: men ≈ 10×kg + 6.25×cm − 5×age + 5. A 70 kg, 175 cm, 30-year-old man ≈ 1,700 kcal/day BMR. BMR is ~60–70% of TDEE for sedentary people; activity multipliers live in TDEE, not here.

When to use this calculator

Use for resting calorie floor before activity. For total daily burn including exercise, use TDEE.

Not what you need? For macros split from total calories, use Macro. For steps-based burn, use Steps to Calories.

Need total daily calories including activity?

This page calculates resting BMR only. For total daily energy expenditure, activity multipliers, and calorie targets for loss or gain, use the TDEE Calculator →

Gender

Male Female

Age (years)

Height (cm)

Weight (kg)

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Mifflin-St Jeor BMR

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Harris-Benedict BMR

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Average BMR

Daily Calorie Needs (TDEE) by Activity Level

Activity Level	Multiplier	Calories/day
Sedentary (little/no exercise)	× 1.200	—
Lightly active (1–3 days/wk)	× 1.375	—
Moderately active (3–5 days/wk)	× 1.550	—
Very active (6–7 days/wk)	× 1.725	—
Super active (2× training/day)	× 1.900	—

What is BMR (Resting Calorie Burn)?

Basal Metabolic Rate (BMR) is the energy your body needs to stay alive at rest — breathing, circulation, cell repair, and temperature regulation — with no exercise or digestion factored in. It typically accounts for 60–70% of total daily burn and depends on age, sex, height, and lean mass.

This calculator returns BMR from validated formulas (Mifflin-St Jeor and Harris-Benedict) in both metric and imperial units. Use BMR when you want the physiological floor — the minimum calories before any activity multiplier — or when comparing formula estimates for clinical and coaching contexts.

BMR alone does not set a weight-loss or maintenance calorie target. For total daily burn including desk work, workouts, and NEAT — plus deficit and surplus bands — use the TDEE Calculator, which applies an activity multiplier to BMR.

BMR Formulas

Mifflin-St Jeor (recommended)

Male: (10 × kg) + (6.25 × cm) − (5 × age) + 5

Female: (10 × kg) + (6.25 × cm) − (5 × age) − 161

Harris-Benedict (classic)

Male: 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age)

Female: 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)

kg = weight in kg cm = height in cm age = age in years

How to Calculate Your BMR

1

Choose Unit System

Select Metric (kg/cm) or Imperial (lbs/ft) using the toggle.
2

Enter Your Details

Input your gender, age, height, and weight accurately.
3

Click Calculate

Both Mifflin-St Jeor and Harris-Benedict results appear instantly.
4

Use the TDEE Table

Multiply your BMR by your activity level to find your total daily calorie needs.

Example Calculation

Female, 30 years old, 165 cm, 65 kg:

Mifflin = (10 × 65) + (6.25 × 165) − (5 × 30) − 161

= 650 + 1031.25 − 150 − 161 = 1,370 kcal/day

Harris-Benedict = 447.593 + (9.247 × 65) + (3.098 × 165) − (4.330 × 30)

= 447.593 + 601.055 + 511.17 − 129.9 = 1,430 kcal/day

TDEE (moderately active × 1.55) ≈ 2,170 kcal/day

How the BMR Calculator Works

Formula, assumptions, and calculation steps for this health tool.

Formula Used

Mifflin-St Jeor: BMR = 10w + 6.25h - 5a + s

Methodology

Health calculators use published screening formulas and common planning rules to estimate body, nutrition, pregnancy, or fitness metrics from user inputs.

Calculation Steps

Enter the personal measurements requested by the tool.
Convert height, weight, age, dates, or activity inputs to standard units.
Apply the health or fitness formula for the selected metric.
Show the estimate with practical ranges or interpretation where available.

Assumptions and Limits

Results are educational estimates, not diagnosis or medical advice.
Individual factors such as medication, pregnancy, and medical history can change interpretation.
Consult a clinician for personal health decisions.

Reference basis: Common public-health and sports-science screening formulas.

Frequently Asked Questions

What is BMR?

Basal Metabolic Rate is the minimum number of calories your body needs to perform basic life-sustaining functions — breathing, circulation, cell production, and temperature regulation — while at complete rest. It accounts for roughly 60–70% of total daily energy expenditure.

Which formula is more accurate — Mifflin or Harris-Benedict?

Studies show the Mifflin-St Jeor equation (1990) is more accurate for most people, with an error margin of around 10%. The original Harris-Benedict formula (1919) tends to overestimate by 5–15%. The revised Harris-Benedict (1984) used here is more accurate than the original.

How can I increase my BMR?

BMR is primarily determined by genetics, age, height, and muscle mass. Building lean muscle through resistance training is the most effective way to raise it, since muscle burns more calories at rest than fat. Eating adequate protein and avoiding very-low-calorie diets also helps preserve metabolic rate.

What is the difference between BMR and TDEE?

BMR is the calories burned at complete rest. TDEE (Total Daily Energy Expenditure) includes all calories burned through daily activities and exercise. TDEE = BMR × activity multiplier. If you eat at your TDEE, you maintain weight; below TDEE you lose weight; above TDEE you gain weight.

Real-World Applications

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Weight Loss Planning

Knowing your TDEE (BMR × activity factor) sets the calorie target for a deficit. A 500 kcal/day deficit below TDEE produces roughly 0.5 kg of fat loss per week.

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Muscle Building (Bulking)

Bodybuilders and strength athletes eat in a calorie surplus above TDEE. BMR is the starting point for calculating how much extra energy to consume for lean gains without excess fat.

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Clinical Nutrition

Hospitals use BMR calculations to determine the minimum calorie requirements for patients recovering from surgery, illness, or malnutrition — particularly those on tube or parenteral feeding.

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Personalised Diet Plans

Nutritionists and dietitians use BMR as the foundation for macronutrient plans, ensuring clients eat enough to support metabolic health while achieving their body composition goals.

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Endurance Sport Training

Marathon runners and cyclists calculate energy needs during multi-day training camps using BMR-derived TDEE to prevent underfuelling, which impairs performance and recovery.

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Metabolic Research

Scientists use BMR measurements to study the effects of diet composition, exercise, ageing, and hormonal therapies on resting energy expenditure in clinical research settings.

Common Mistakes

Eating at BMR, Not TDEE

BMR is the bare minimum for survival at rest. Eating only at BMR while active will create a severe deficit. Always multiply BMR by your activity factor to get TDEE before setting calorie targets.

Overestimating Activity Level

Most people overestimate their activity level. Choosing "highly active" when actually "lightly active" inflates TDEE by 300–500 kcal/day, causing unintended weight gain.

Not Adjusting for Weight Changes

BMR decreases as body weight decreases. Recalculate BMR every 5–10 kg of weight loss to avoid hitting a plateau caused by eating at a level that is no longer a deficit.

Ignoring Body Composition

The Mifflin-St Jeor formula uses weight, not lean mass. Two people at the same weight but different muscle-to-fat ratios have different true BMRs. Use Katch-McArdle if body composition is known.

Treating Formula Results as Exact

BMR formulas predict values within ~10% accuracy on average. Use the result as a starting point, then track actual weight change over 2–3 weeks and adjust calories accordingly.

BMR Formula Comparison

Formula	Year	Best For	Accuracy
Mifflin-St Jeor	1990	General adult population	Highest — ±5–10%
Harris-Benedict (revised)	1984	General adult population	Good — ±10–15%
Katch-McArdle	1996	Known lean body mass	Most precise when LBM known
Schofield	1985	Children, elderly	Validated for specific age groups

References

Mifflin, M. D. et al. A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals. American Journal of Clinical Nutrition, 1990.
Harris, J. A. & Benedict, F. G. A Biometric Study of Basal Metabolism in Man. Carnegie Institution, 1919.
Katch, F. I. et al. Prediction of Body Density from Simple Anthropometric Measurements. Human Biology, 1986.
Academy of Nutrition and Dietetics. Position Paper: Weight Management. Journal of the Academy of Nutrition and Dietetics, 2016.
Frankenfield, D. et al. Comparison of Predictive Equations for Resting Metabolic Rate in Healthy Nonobese and Obese Adults. Journal of the American Dietetic Association, 2005.