Estimate your Basal Metabolic Rate using the Mifflin-St Jeor equation — the formula recommended by the Academy of Nutrition and Dietetics.
BMR is the minimum calories your body burns at complete rest. According to research in the American Journal of Clinical Nutrition, the Mifflin-St Jeor equation is approximately 5% more accurate than Harris-Benedict. BMR accounts for 60-70% of your total daily burn. Never eat below your BMR — cut from TDEE instead.
Written by Ash K · Last updated: June 2026 · Sources cited below
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — just to keep you alive. Breathing, circulation, cell production, body temperature regulation. If you lay in bed all day doing nothing, BMR is what you'd still burn.
This calculator uses the Mifflin-St Jeor equation, which a 2005 systematic review in the Journal of the American Dietetic Association found to be the most accurate predictive equation for most populations.
Key Takeaway: BMR is your minimum calorie burn — the energy cost of staying alive. It accounts for 60–70% of your total daily energy expenditure (TDEE). The Mifflin-St Jeor formula: Men = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 5. Women = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161. BMR is NOT your calorie target — TDEE is.
| Factor | Effect on BMR |
|---|---|
| More muscle mass | Higher BMR (muscle is metabolically active) |
| Larger body | Higher BMR (more tissue to maintain) |
| Younger age | Higher BMR (declines ~2–8% per decade after 30) |
| Male sex | Higher BMR (more muscle mass on average) |
| Thyroid function | Hypo = lower BMR, hyper = higher BMR |
BMR is your floor. TDEE is your actual burn. Never set your calorie target at BMR — that creates a deficit equal to all your daily activity, which is too aggressive.
Example: BMR = 1,500 cal. Activity multiplier = 1.55 (moderate). TDEE = 2,325 cal. Eating at 1,500 = an 825 cal deficit — unsustainable, muscle-wasting, and metabolically suppressive.
The correct approach: eat relative to TDEE. For fat loss: TDEE minus 300–500. For maintenance: at TDEE. For muscle gain: TDEE plus 250–500.
For your full daily energy expenditure, use our TDEE calculator. For a detailed comparison, see BMR vs TDEE explained.
Warning: Never eat below your BMR for extended periods without medical supervision. Sustained intake below BMR disrupts thyroid function, suppresses reproductive hormones, impairs immune response, and accelerates muscle loss. Your BMR is your body's operating minimum — not a diet target.
Bottom Line: BMR tells you what your body needs just to function. It's the foundation of TDEE, which is your actual calorie target. Calculate BMR here, then use the TDEE calculator to find your real daily burn. Eat relative to TDEE, never below BMR.
BMR Formulas Compared — Published Accuracy Data
What is a normal BMR?
BMR varies widely. Average adult woman: 1,200–1,500 cal. Average adult man: 1,500–1,800 cal. Athletes and larger individuals can have BMRs above 2,000. There's no single "normal."
How do I calculate my BMR?
Mifflin-St Jeor: Men = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 5. Women = same formula but − 161 instead of − 5. Or use this calculator.
Should I eat at my BMR to lose weight?
No. Eating at BMR puts you in too aggressive a deficit. Calculate your TDEE and eat 300–500 below it for sustainable fat loss.
BMR vs TDEE — Where Your Calories Go
This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health.