How BMR is calculated
The Mifflin-St Jeor equation is the modern standard and the primary result here:
Men: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age + 5
Women: BMR = 10·weight(kg) + 6.25·height(cm) − 5·age − 161
For a 30-year-old man at 180 cm and 75 kg: 750 + 1,125 − 150 + 5 = 1,730 calories a day at rest. Imperial entries are converted first (inches × 2.54, pounds × 0.4536).
From BMR to daily calories
Your body burns more than BMR once you move. Multiply by an activity factor to estimate maintenance calories (TDEE):
- Sedentary (little exercise): BMR × 1.2
- Lightly active (1–3 days/week): BMR × 1.375
- Moderately active (3–5 days): BMR × 1.55
For a full activity breakdown and weight-goal targets, use the calorie calculator.
Frequently asked questions
What is BMR?
Basal metabolic rate is the number of calories your body burns at complete rest just to keep you alive — powering your heart, brain, breathing, and other basic functions. It is the largest part of your daily calorie burn, before any activity is added.
How is BMR calculated?
The most accurate common equation is Mifflin-St Jeor: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women the last term is −161. The older Harris-Benedict equation gives a similar figure and is shown for comparison.
What is the difference between BMR and TDEE?
BMR is calories burned at rest. Total daily energy expenditure (TDEE) is BMR multiplied by an activity factor to include movement and exercise. A sedentary person burns about 1.2 × BMR; lightly active, about 1.375 ×. Use a calorie or TDEE calculator for the full breakdown.
Should I eat my BMR number of calories?
No — BMR is a resting baseline, not a target. Eating only your BMR while living a normal active life would create a large deficit. Base intake on your TDEE, then adjust up or down for your goal.
Why do the two formulas give different numbers?
Mifflin-St Jeor was developed more recently and tends to be more accurate for most modern adults, while Harris-Benedict (revised in 1984) often reads slightly higher. Both are estimates — your true BMR depends on muscle mass, genetics, and other factors a formula can't capture.
Disclaimer: BMR equations are estimates and don't account for body composition or medical conditions. This is for educational purposes only and is not medical or nutritional advice.