BMR Calculator
Find out how many calories your body burns at complete rest
What is BMR?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions while at complete rest. This includes breathing, circulation, cell production, and organ function. Think of it as the minimum amount of fuel your body needs just to stay alive.
BMR typically accounts for 60 to 75 percent of your total daily calorie expenditure, making it the largest component of your energy needs. Even if you did nothing but lie still all day, your body would still burn this many calories.
Mifflin-St Jeor vs Harris-Benedict
This calculator uses the Mifflin-St Jeor equation, which was developed in 1990 and is considered the most accurate formula for estimating BMR in the general population. Studies have shown it to be within 10 percent of measured BMR for most people. The older Harris-Benedict equation, developed in 1919, tends to overestimate BMR by around 5 percent.
For lean, muscular individuals the Katch-McArdle formula can be more accurate as it accounts for lean body mass. However this requires knowing your body fat percentage. Use our Body Fat Calculator first if you want the most precise result.
How to Use Your BMR
Your BMR on its own is not a calorie target — it is the floor, not the goal. To find your actual daily calorie needs you multiply your BMR by an activity factor to get your TDEE. From there you adjust up or down depending on whether your goal is weight loss, maintenance, or muscle gain. Use our TDEE Calculator to get your complete calorie picture.
BMR Calculator — Frequently Asked Questions
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body needs to maintain basic life functions — breathing, circulation, cell production and temperature regulation — while at complete rest. It represents 60–70% of total daily calorie burn for most people.
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is the most accurate BMR formula for the general population according to the Academy of Nutrition and Dietetics. For men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. For women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161.
Can I increase my BMR?
Yes. The most effective way to raise your BMR is to build muscle through resistance training, as muscle burns more calories at rest than fat. Staying hydrated and avoiding very low calorie diets also helps prevent BMR suppression.
What is the difference between BMR and RMR?
BMR is measured under very strict conditions — fasted and fully rested. RMR (Resting Metabolic Rate) is measured under less strict conditions and is typically 10–20% higher. Most online calculators estimate RMR though the terms are often used interchangeably.