What is BMR?
Basal metabolic rate is the minimum number of calories your body needs for essential functions such as breathing, blood circulation and temperature control.
BMR Calculator – Estimate BMR, RMR & TDEE
Use this free BMR calculator to estimate basal metabolic rate, resting metabolic rate, and total daily energy expenditure using popular formulas and activity levels.
BMR Calculator
Enter your age, gender, height, weight, and activity level to calculate BMR, RMR, and TDEE.
BMR/RMR Calculator
Calculate your basal metabolic rate (BMR) and resting metabolic rate (RMR).
Results
BMR: — kcal/day
RMR: — kcal/day
Estimated TDEE: — kcal/day
What is RMR?
Resting metabolic rate is similar to BMR, but usually about 10% higher because it includes low-effort daily living activity.
How to Use
- Select your gender and age.
- Choose US or Metric units.
- Enter your height and weight.
- Select the BMR equation and activity level.
- Click Calculate to view BMR, RMR, and estimated TDEE.
How This Calculator Works
This calculator converts your body measurements into metric values and applies one of three common metabolic equations: Mifflin-St Jeor, Revised Harris-Benedict, or Katch-McArdle. It also estimates RMR and TDEE based on your selected activity level.
Frequently Asked Questions
What is BMR?
BMR is the number of calories your body needs at complete rest to maintain basic life functions.
What is the difference between BMR and RMR?
RMR is similar to BMR but is usually slightly higher because it includes minimal daily activity at rest.
What is TDEE?
TDEE stands for total daily energy expenditure and estimates how many calories you burn in a day including activity.
What Is Basal Metabolic Rate (BMR)?
Your basal metabolic rate (BMR) is the minimum energy your body needs to perform vital functions. For many adults, BMR is the largest share of daily energy expenditure and is influenced by body size, lean mass, sex, age, hormones, illness and more.
Factors that affect BMR
- Body size and amount of lean muscle tissue.
- Body fat amount and distribution.
- Sex, age, genetics, race/ethnicity.
- Environmental temperature, fasting, illness/injury, thyroid levels, stimulants.
- Life stages such as growth, pregnancy, lactation and menopause.
Common equations used
Mifflin-St Jeor: Men: 10W + 6.25H - 5A + 5, Women: 10W + 6.25H - 5A - 161.
Revised Harris-Benedict: Men: 13.397W + 4.799H - 5.677A + 88.362, Women: 9.247W + 3.098H - 4.330A + 447.593.
Katch-McArdle: 370 + 21.6 × (1 - F) × W (uses body fat percentage).
BMR variables and practical notes
Muscle mass, age, weather, diet patterns, pregnancy/menopause, genetics and supplements can all affect your metabolism. These calculators are estimates and not substitutes for calorimetry testing or medical guidance.
Modern interpretation
Even with high-quality equations, meaningful individual variance remains. Use BMR/TDEE as a baseline and adjust based on tracked outcomes over time (body weight trend, performance, hunger, sleep and overall wellbeing).
Reference
Johnstone AM, et al. Factors influencing variation in basal metabolic rate. Am J Clin Nutr. 2005;82:941-948.