BMR Calculator

BMR Calculator — Basal Metabolic Rate & Daily Calories
Metabolic Estimator

Your Basal Metabolic Rate

Find out how many calories your body burns at rest — and how many you actually need every day.

Mifflin–St Jeor Instant TDEE Metric & Imperial
BMR Calculator
Basal Metabolic Rate & Daily Calorie Needs
Most Accurate Formula
Gender
Age 30 yrs
Units
Height
cm
Weight
kg
Your Basal Metabolic Rate
1,649
kcal / day
Energy required at complete rest
(10 × 70) + (6.25 × 175) − (5 × 30) + 5
Using Mifflin–St Jeor
Daily Calorie Needs (TDEE)
Tap an activity level for your recommendation
Weight Loss
—
−500 kcal deficit
Maintenance
—
Stay at current weight
Mild Gain
—
+250 kcal surplus
Muscle Gain
—
+500 kcal surplus
Estimated Macros at Maintenance
Protein
—
Carbs
—
Fat
—
Not medical advice. Results are estimates. Most accurate for general population

What is Basal Metabolic Rate (BMR)?

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to sustain basic life functions at complete rest — breathing, circulating blood, regulating temperature, cell production, and keeping your vital organs running.

BMR typically accounts for 60–75% of your total daily calorie burn. The rest comes from physical activity and digestion of food.

How to Use This BMR Calculator

This calculator uses the Mifflin–St Jeor Equation, the most accurate formula for most people. Results update instantly as you change inputs.

  • Choose units (Metric or US Imperial)
  • Enter your age, gender, height, and weight
  • View your BMR and TDEE across different activity levels
  • Tap any activity level to get a personalised calorie recommendation

BMR Calculation Formulas

Mifflin–St Jeor Recommended
Men: BMR = 10W + 6.25H − 5A + 5

Women: BMR = 10W + 6.25H − 5A − 161
W = kg · H = cm · A = years
Revised Harris–Benedict
Men: 13.397W + 4.799H − 5.677A + 88.362

Women: 9.247W + 3.098H − 4.330A + 447.593
Older formula, slightly less accurate today
Katch–McArdle
BMR = 370 + 21.6 × (1 − F) × W

Best when you know your body fat %.
F = body fat fraction

Factors That Affect Your BMR

Muscle Mass

Muscle burns more calories at rest than fat. Strength training raises your BMR over time.

Age

BMR declines with age mainly due to muscle loss. Strength training helps slow this decline.

Genetics

Some people naturally have higher or lower metabolic rates due to hereditary factors.

Climate & Temperature

Cold environments and fever increase BMR as the body works harder to maintain temperature.

Diet & Fasting

Severe calorie restriction can lower BMR by up to 30% as the body enters conservation mode.

Hormones & Pregnancy

Pregnancy significantly increases BMR. Hormonal changes also affect metabolic rate.

How Accurate Are BMR Calculators?

BMR calculators provide excellent estimates but are not 100% precise for every person. Research shows there is still significant unexplained variation in metabolic rate between individuals.

For best results, use this calculator as a starting point and track your actual weight and energy levels over 2–4 weeks, then adjust accordingly.

Important: BMR and TDEE are starting points. Track real-world results and adjust as needed.
BMI Calculator Calorie Calculator Ideal Weight Calculator Body Fat Calculator Macro Calculator Pregnancy Calculator
Reference: Johnstone AM et al. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. Am J Clin Nutr. 2005;82(5):941–948.
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