Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic life functions — breathing, circulation, cell production — while completely at rest. It's the foundation for estimating total daily calorie needs; see our calorie calculator to apply an activity multiplier on top of BMR.
The formula
This is the Mifflin-St Jeor equation, generally considered more accurate for most adults than the older Harris-Benedict formula.
Worked example
For a 30-year-old woman weighing 60 kg at 165 cm: BMR = 10×60 + 6.25×165 − 5×30 − 161 = 600 + 1,031.25 − 150 − 161 = 1,320.25, or roughly 1,320 kcal/day.
Why BMR alone isn't your full calorie need
BMR only accounts for calories burned at rest — it does not include digestion, daily movement, or exercise. Total Daily Energy Expenditure (TDEE), which adds an activity multiplier to BMR, is the more relevant number for weight management. Use the calorie calculator for that full picture.
Common mistakes
- Treating BMR as your total calorie budget. Eating exactly your BMR ignores all daily activity and is typically far too low for most people.
- Using outdated formulas. Mifflin-St Jeor generally outperforms older equations like Harris-Benedict for most adults.
Frequently asked questions
What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest to maintain basic life functions like breathing and circulation.
What formula does this calculator use?
The Mifflin-St Jeor equation, which uses weight, height, age, and sex, and is widely regarded as one of the more accurate predictive formulas available.
Should I eat exactly my BMR to lose weight?
No. BMR excludes activity and digestion. Total Daily Energy Expenditure (TDEE), which applies an activity multiplier to BMR, is the more appropriate baseline for calorie planning.
References
- National Institutes of Health — Background on basal metabolic rate and energy expenditure