BMR Calculator
Your Basal Metabolic Rate — the calories your body burns at complete rest — compared across the three leading formulas.
What Is BMR?
BMR stands for Basal Metabolic Rate — the number of calories your body needs to perform its most basic functions while completely at rest. These functions include breathing, maintaining your heartbeat, supporting brain activity, regulating body temperature, and repairing cells. For most adults, BMR accounts for approximately 60–70% of the total calories burned each day. The remaining calories come from digesting food, daily movement, and physical activity.
What Does BMR Measure?
Your BMR represents the calories your body needs to perform essential life functions while you are completely at rest. These functions include breathing, circulating blood, supporting brain activity, regulating body temperature, and repairing cells. This stat does not include calories burned through exercise, daily movement, or food digestion. Instead, it measures the minimum amount of energy your body requires to stay alive each day.
BMR vs. TDEE
BMR and Total Daily Energy Expenditure (TDEE) both estimate calorie needs, but they measure different parts of your daily energy use. BMR shows the calories your body burns at complete rest, while TDEE includes BMR plus the calories used for digestion, physical activity, exercise, and other everyday movements. If BMR is your body's baseline energy requirement, TDEE represents your total daily calorie expenditure.
BMR | TDEE |
Calories burned at complete rest | Total calories burned throughout the day |
Supports basic body functions | Includes all daily activities and exercise |
Baseline energy requirement | Daily calorie requirement for your lifestyle |
BMR Calculator Overview
BMR Calculator is an online tool that estimates your Basal Metabolic Rate based on your age, gender, height, and weight. It applies established BMR formulas to calculate the number of calories your body needs each day while completely at rest. The estimated result provides a practical starting point for understanding your resting energy requirements and can support calorie planning, weight management, and fitness goals.
Three Formulas, One Goal
BMR Calculator includes the three most widely recognized equations, allowing you to compare results or choose the one that best matches your body composition.
Mifflin-St Jeor (women): 10×kg + 6.25×cm − 5×age − 161 Harris-Benedict (men): 13.397×kg + 4.799×cm − 5.677×age + 88.362 Harris-Benedict (women): 9.247×kg + 3.098×cm − 4.330×age + 447.593 Katch-McArdle: 370 + 21.6 × lean body mass (kg)
- Mifflin-St Jeor (1990) — Our default with the most accurate for the general adult population.
- Harris-Benedict (1919, revised 1984) — Classic formula with slightly higher estimates.
- Katch-McArdle — Best for known lean body mass to know the body fat percentage.
Easy-to-Understand Guidelines to Use This Calculator
BMR Calculator only takes a few easy steps to estimate your resting calorie needs:
- Choose Your Units: Select US Units or Metric, then choose your gender.
- Enter Your Information: Fill in your age, height, weight, and body fat percentage if available.
- Calculate Your BMR: Click Calculate My BMR to estimate your resting calorie needs.
- Review Your Results: Compare your BMR estimates and check your daily calorie needs for each activity level.
Accurate body measurements produce more reliable BMR estimates. So, you should update your information regularly to reflect changes in your weight, age, or body composition.
Frequently asked questions
BMR vs TDEE — what is the difference?
BMR measures calories burned at rest, while TDEE includes daily activities, exercise, and food digestion. Daily calorie goals should be based on TDEE, not BMR.
Which BMR formula is most accurate?
Mifflin-St Jeor is the best choice for most adults. Otherwise, Katch-McArdle can be more accurate if you know your body fat percentage.
Does metabolism really slow with age?
It’s just a little bit! Large 2021 pooled data (Science, Pontzer et al.) shows metabolism stays fairly stable from ages 20 to 60 after accounting for body size.
Can I raise my BMR? (→ transform a heading of the main content)
Yes, but only gradually! Building muscle and eating enough protein can increase your BMR, while very restrictive diets may lower it. It makes gradual calorie changes a better long-term approach.
References
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure. Am J Clin Nutr, 1990.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr, 1984.
- Pontzer H, et al. Daily energy expenditure through the human life course. Science, 2021.