This free BMR calculator gives you instant results with no signup required. All calculations run in your browser — nothing is sent to any server.
BMR Calculator Online Free
Calculate your basal metabolic rate and total daily energy expenditure (TDEE) using the Mifflin-St Jeor equation. Get daily calorie targets for weight loss, gain or maintenance.
BMR Formula Mifflin-St Jeor
Men: BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) + 5. Women: BMR = (10 x weight kg) + (6.25 x height cm) - (5 x age) - 161. The 1990 Mifflin equation is more accurate than older Harris-Benedict.
TDEE Calculator
TDEE = BMR x activity factor. Sedentary (desk job): 1.2. Light exercise 1-3 days: 1.375. Moderate exercise 3-5 days: 1.55. Heavy exercise 6-7 days: 1.725. Physical job plus exercise: 1.9.
Calories to Lose Weight Calculator
A 500 calorie daily deficit leads to approximately 0.5 kg fat loss per week. Multiply your TDEE by 0.85 for a 15% deficit — safer for preserving muscle. Never go below 1,200 calories (women) or 1,500 (men).
BMR vs TDEE Difference
BMR is what you burn lying completely still for 24 hours. TDEE is your actual daily burn including all movement. TDEE is always higher. For weight management, TDEE is the number that matters.
Frequently Asked Questions
What is BMR calculator?
A BMR calculator estimates how many calories your body burns at complete rest in 24 hours. It uses your weight, height, age and gender. Multiply BMR by your activity level to get TDEE — the actual calories you burn each day.
Which BMR formula is most accurate?
Mifflin-St Jeor (1990) is the most accurate for most adults. It was validated on a diverse population including overweight individuals. The older Harris-Benedict formula from 1919 tends to overestimate by 5-10%.
How many calories should I eat to lose weight?
Subtract 500 from your TDEE for approximately 0.5 kg loss per week. A 250 calorie deficit gives slower but more sustainable loss. Do not cut more than 25% of TDEE — extreme deficits cause muscle loss and metabolic slowdown.
Does BMR change with age?
Yes. BMR decreases by about 2-3% per decade after age 20 as muscle mass declines with age. Strength training is the most effective way to slow this decline and keep BMR higher as you get older.
Is BMR the same for men and women?
No. Men have higher BMR because they have more muscle mass on average. The Mifflin-St Jeor formula accounts for this with +5 for men and -161 for women in the formula. A 30-year-old man and woman of same height and weight will have different BMR values.