What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest just to stay alive: to breathe, pump blood, keep a steady temperature and repair cells. For most people it accounts for 60–70% of all calories burned in a day. Your Total Daily Energy Expenditure (TDEE) adds the calories used for everyday movement and exercise. Knowing both helps you plan meals to lose, maintain or gain weight.
How to use the calculator
- Enter your sex, age, weight and height.
- Pick the activity level that honestly describes a typical week.
- Read your BMR, your maintenance calories and suggested calorie targets for gradual weight change.
The equations
Mifflin-St Jeor (men): BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Mifflin-St Jeor (women): BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
TDEE = BMR × activity factor
The Mifflin-St Jeor equation, published in 1990, is considered one of the most accurate formulas for healthy adults. The revised Harris-Benedict equation is shown for comparison. Activity factors range from 1.2 for sedentary people to 1.9 for very physical work plus training.
Example: a 30-year-old man weighing 70 kg and 172 cm tall: BMR = 700 + 1,075 − 150 + 5 = 1,630 kcal. If he is lightly active (× 1.375), he needs about 2,241 kcal a day to maintain his weight.
Calories and weight change
A deficit of about 500 kcal a day leads to roughly 0.5 kg of weight loss per week for many people, though real results vary. Slow, steady changes are easier to keep up and help preserve muscle. Very low calorie diets can cause tiredness, nutrient deficiencies and muscle loss, and should only be followed under medical supervision. As your weight changes, recalculate, because your BMR changes too.
Frequently asked questions
Why is my BMR different on another website?
Different sites use different equations. Results within about 100 kcal are normal.
Does muscle increase BMR?
Yes. Muscle tissue uses more energy than fat at rest, which is why strength training helps long-term weight management.
How many calories do my workouts burn?
Estimate them with the Calories Burned Calculator.
These are estimates for healthy adults. They are not medical or nutritional advice; consult a doctor or registered dietitian for a personal plan, especially if you are pregnant or have a health condition.