BMR Calculator
Estimate your BMR with Mifflin-St Jeor and Harris-Benedict equations. Enter age, sex, weight, and height to get your daily calorie baseline instantly.
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy
BMR Calculator Formula
BMR (Mifflin-St Jeor) = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5 (male) or -161 (female)
The Mifflin-St Jeor equation calculates BMR based on weight, height, age, and gender. It's the most accurate formula for people of normal weight, overweight, and obese categories. The result represents calories burned at complete rest over 24 hours.
BMR Calculator — Worked Examples
Example 1: Male BMR Calculation
Problem:Calculate BMR for a 30-year-old male, 180 lbs (81.6 kg), 5'10\" (177.8 cm) using Mifflin-St Jeor.
Solution:BMR = 10 x 81.6 + 6.25 x 177.8 - 5 x 30 + 5\nBMR = 816 + 1,111.25 - 150 + 5\nBMR = 1,782 calories/day\nHourly burn rate = 1,782 / 24 = 74.3 cal/hour
Result:BMR: 1,782 calories per day (74.3 cal/hour)
Example 2: Female BMR with Activity Levels
Problem:Calculate BMR and TDEE for a 25-year-old female, 135 lbs (61.2 kg), 5'5\" (165.1 cm), moderately active.
Solution:BMR = 10 x 61.2 + 6.25 x 165.1 - 5 x 25 - 161\nBMR = 612 + 1,031.9 - 125 - 161 = 1,358 cal/day\nTDEE = 1,358 x 1.55 = 2,105 cal/day\nWeight loss (500 deficit) = 1,605 cal/day
Result:BMR: 1,358 cal | TDEE: 2,105 cal | Weight loss: 1,605 cal
BMR Calculator — Frequently Asked Questions
What is BMR (Basal Metabolic Rate)?
BMR is the number of calories your body burns at complete rest to maintain vital functions like breathing, blood circulation, cell production, nutrient processing, and temperature regulation. It represents the minimum energy your body needs to survive if you did nothing but lie in bed all day. BMR typically accounts for 60-75% of your total daily calorie expenditure. Factors affecting BMR include age (decreases ~2% per decade after 20), gender (men typically have higher BMR due to more muscle mass), body composition (muscle burns more than fat), and genetics.
What is the difference between BMR and RMR?
BMR (Basal Metabolic Rate) and RMR (Resting Metabolic Rate) are often used interchangeably, but there's a slight technical difference. BMR is measured under very strict conditions - after 8 hours of sleep, 12 hours of fasting, in a dark room at comfortable temperature. RMR is measured under less restrictive conditions and is typically 10-20% higher than BMR because it includes some minimal daily activity. In practice, most calculators and nutritionists use them interchangeably since the difference is small and both serve the same purpose: estimating your baseline calorie needs.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation (1990) is considered the most accurate for most people, as validated by the American Dietetic Association in 2005. It's accurate within 10% for about 82% of people. The revised Harris-Benedict equation (1984) is slightly less accurate but still widely used. The Katch-McArdle formula is most accurate for lean, muscular individuals because it factors in lean body mass rather than total weight. If you know your body fat percentage, Katch-McArdle is preferred. For general use without body composition data, Mifflin-St Jeor is the best choice.
How can I increase my BMR?
The most effective way to increase BMR is building lean muscle mass through resistance training - muscle tissue burns about 6 calories per pound per day at rest, compared to 2 calories for fat. Other strategies include: staying hydrated (dehydration slows metabolism), eating adequate protein (thermic effect of protein is 20-30% of calories consumed), getting enough sleep (sleep deprivation reduces BMR by 5-20%), managing stress (cortisol promotes fat storage), and avoiding very low calorie diets (they trigger metabolic adaptation). High-intensity interval training (HIIT) also temporarily elevates BMR for 24-48 hours post-exercise.