π₯ BMR Calculator
Calories your body burns at complete rest.
For informational purposes only, not medical advice. Consult a healthcare professional.
What BMR Actually Means
Your Basal Metabolic Rate is the calories your body burns doing nothing at all: keeping your heart beating, lungs breathing, brain running, and body temperature stable. For most people it is 60 to 70 percent of total daily calorie burn, which makes it the foundation of every calorie target. This calculator uses the Mifflin-St Jeor equation, the formula the Academy of Nutrition and Dietetics considers most accurate for the general population: for men, BMR = 10 x weight in kg + 6.25 x height in cm - 5 x age + 5; for women, the same minus 161 instead of plus 5.
The older Harris-Benedict equation still appears on many sites, but validation studies found Mifflin-St Jeor predicts resting burn within 10 percent for more people. No formula is perfect: very muscular people burn more than predicted, and very high body fat percentages burn less per pound, because muscle is metabolically expensive and fat is cheap.
From BMR to Daily Calories
BMR is not your daily target; it is the floor. Multiply by an activity factor to get TDEE (total daily energy expenditure): 1.2 for sedentary, 1.375 for light activity, 1.55 for moderate, 1.725 for very active, 1.9 for athletes. A 30-year-old man, 5-foot-8, 170 pounds: BMR = 10 x 77.1 + 6.25 x 172.7 - 5 x 30 + 5 = 1,705 calories. At moderate activity (x1.55), TDEE is about 2,643. To lose a pound a week, eat roughly 500 below TDEE, but never below BMR for long: chronic under-eating below BMR triggers metabolic adaptation, fatigue, and muscle loss.
What Moves Your BMR
Muscle mass is the biggest lever you control: each pound of muscle burns roughly 6 calories a day at rest versus 2 for fat. Age shaves 1 to 2 percent per decade after 40, mostly through muscle loss, which strength training offsets. Crash diets lower BMR temporarily as the body conserves energy; refeeds and resistance training restore it. Thyroid disorders, pregnancy, and some medications shift it too, which is one reason to check with a doctor if your real-world results diverge wildly from the math. For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the Mifflin-St Jeor equation?
The most validated BMR formula: for men, 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5; for women, the same with -161 instead of +5. The Academy of Nutrition and Dietetics considers it the most accurate for the general population.
How is BMR different from TDEE?
BMR is calories burned at complete rest. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor (1.2 to 1.9), covering everything you do all day. Use TDEE for calorie targets, BMR as the never-go-below floor.
Why is my friend's BMR higher at the same weight?
Muscle burns about 6 calories per pound daily at rest versus 2 for fat, so muscular people have higher BMRs. Age, sex, and height also matter. Two people at 170 pounds can differ by 200+ calories.
Should I eat below my BMR to lose weight?
No, not for long. Chronic eating below BMR drives metabolic adaptation, fatigue, hair loss, and muscle loss. Set your deficit from TDEE (usually TDEE minus 300 to 500), which keeps you safely above BMR.
Does building muscle raise BMR?
Yes. Each pound of muscle adds roughly 6 calories a day to BMR. Ten pounds of new muscle raises daily burn by about 60 calories, which compounds to meaningful fat loss over a year without extra dieting.