BMR & TDEE Calculator

Calculate your Basal Metabolic Rate and Total Daily Energy Expenditure using Mifflin-St Jeor or Harris-Benedict formulas. Get calorie targets for fat loss, maintenance, and muscle gain.

Mifflin-St Jeor (Male): (10 × kg) + (6.25 × cm) − (5 × age) + 5

Activity Level Reference

SedentaryLittle or no exercise×1.2
Lightly ActiveLight exercise 1–3 days/week×1.375
Moderately ActiveModerate exercise 3–5 days/week×1.55
Very ActiveHard exercise 6–7 days/week×1.725
Extra ActiveVery hard exercise & physical job×1.9

What Is BMR?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and cells functioning. It typically accounts for 60–75% of your total daily calorie expenditure and is influenced by your body composition, age, sex, and genetics.

Mifflin-St Jeor vs Harris-Benedict: Mifflin-St Jeor (1990) is considered more accurate for most people and is preferred by registered dietitians. Harris-Benedict (1919, revised 1984) tends to overestimate BMR by 5% on average, but is still widely cited. Both are estimates — actual BMR can vary ±10% from predictions based on body composition.

TDEE: The Number That Actually Matters

Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor. This is the number you actually need to think about for weight management. Eat below your TDEE to lose weight; above it to gain.

Common targets: A 500 kcal daily deficit produces roughly 1 lb/week of fat loss (3,500 kcal = ~1 lb fat). A 300 kcal surplus is a conservative lean-bulk target that minimizes fat gain while supporting muscle protein synthesis. These are starting points — adjust based on actual progress.

Accuracy limits: Activity multipliers are population averages. People often overestimate activity level and underestimate food intake. If your weight isn't changing at "maintenance", try tracking actual food intake for 2 weeks and compare to your TDEE.

Frequently Asked Questions

What is the difference between BMR and TDEE?
BMR is the calories your body burns at complete rest just to stay alive. TDEE includes all daily activity — exercise, walking, even fidgeting — and is the number you actually need for nutrition planning.
Which formula is more accurate, Mifflin-St Jeor or Harris-Benedict?
Mifflin-St Jeor is considered more accurate for modern populations and is recommended by the American Dietetic Association. Harris-Benedict tends to slightly overestimate. Try both and the difference is usually 50-100 calories.
Why am I not losing weight at my calculated deficit?
TDEE calculators are estimates with 10-15% error margins. Track your actual intake and weight for 2-3 weeks to calibrate your real TDEE. If weight is stable, your true TDEE equals your current intake.
Does metabolism slow with age?
Yes, BMR decreases about 1-2% per decade after age 20, mainly due to muscle loss. Resistance training helps counteract this by preserving metabolically active tissue.
Should I eat below my BMR?
Generally no. Eating below BMR long-term can cause muscle loss, nutrient deficiencies, hormonal disruption, and metabolic adaptation. Set your deficit from TDEE, not BMR.

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This calculator is for informational purposes only and does not constitute medical advice. BMR and TDEE estimates are population averages and may not reflect your individual metabolism. Always consult a qualified healthcare provider or registered dietitian for personalized nutrition guidance.