BMR Calculator
Your Basal Metabolic Rate is the number of calories your body burns just staying alive – breathing, circulation, cell repair. It is the foundation every calorie plan is built on.
Fill in your details and your BMR appears here instantly.
Your BMR
- kcal/day at complete rest
Daily calories at each activity level
This table is your BMR multiplied by standard activity factors – the same math behind our TDEE calculator.
What is BMR?
BMR is the energy your body needs over 24 hours at complete rest. For most people it makes up 60-75% of everything they burn in a day – far more than any workout. Muscle tissue burns more than fat tissue, which is why two people of the same weight can have meaningfully different BMRs.
The Mifflin-St Jeor equation
Introduced in 1990 and validated repeatedly since, Mifflin-St Jeor is the equation the Academy of Nutrition and Dietetics considers the most reliable for healthy adults:
Men: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5Women: 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
That is exactly what this calculator runs. Note it uses weight, height, age and sex only – it does not know your body composition, so very muscular or very lean people can sit 5-10% off the estimate.
BMR vs TDEE
BMR is what you burn doing nothing. TDEE is what you burn living your actual life – BMR plus work, walking, training and digestion. Use BMR to understand your floor; use the TDEE calculator to plan what to eat, and the calorie deficit calculator to plan fat loss.
Frequently asked questions
Can I raise my BMR?
Slowly, yes. Building muscle is the most reliable lever, and eating enough protein supports it. Drastic dieting does the opposite – severe restriction can lower measured expenditure, one reason crash diets stall.
Is it safe to eat below my BMR?
Eating slightly below BMR happens on many successful diets because TDEE, not BMR, is your true budget. What matters is staying above roughly 1,200 kcal (women) or 1,500 kcal (men) unless a doctor supervises you.
Why does BMR drop with age?
Mostly because of gradual muscle loss and hormonal change. The decline is roughly 1-2% per decade after early adulthood, and strength training blunts a large part of it.
How accurate is this number?
Typically within about 10% of a lab measurement for healthy adults. Track your weight for two to three weeks at a calculated intake and adjust from real data.