🧮 BMR Calculator
BMR – the number of calories the body burns at rest over 24 hours. It is the basis for calculating TDEE.
📐 Mifflin-St Jeor Formula
For Men: BMR = 10×weight + 6.25×height − 5×age + 5
For Women: BMR = 10×weight + 6.25×height − 5×age − 161
📊 BMR Statistics and Facts
What Is BMR?
Basal metabolic rate (BMR) is the number of calories the body burns at rest while maintaining vital functions. It accounts for ~60–70% of total daily calorie expenditure.
Metabolic Slowing
After age 30, BMR slows by an average of 1–2% per decade. However, regular strength training can slow or even stop this process.
Sex Differences
Men's BMR is on average 10–15% higher than that of women of the same age and weight due to greater muscle mass. Each kilogram of muscle increases BMR by ~13 kcal/day.
💡 Practical Tips
- Increase Muscle Mass — this is the only effective way to raise BMR. Each additional kg of muscle increases BMR by ~13 kcal per day.
- Do Not Starve — too low a calorie intake (<1200 kcal) can reduce BMR by 15–20%. The body enters a "saving mode".
- Eat Enough Protein — protein thermogenesis (TEF) accounts for ~20–30% of the calories from protein consumed. For comparison: carbohydrates 5–10%, fats 0–3%.
- Track, Do Not Guess — carefully track your calorie intake and weight for 2 weeks. If your weight is stable, you have found your true TDEE.
📖 How to Interpret the Result
The resulting number shows approximately how many calories your body burns in complete rest per day — for breathing, heart function, and temperature maintenance. It is not “how much you can eat,” but only the lower bound of your daily needs.
If the result seems high or low, do not worry — it is an indicative value. What matters most is how you use it: BMR is used for further TDEE calculation, not as a final goal.
🔁 From BMR to TDEE
BMR is multiplied by an activity factor to obtain total daily calorie needs (TDEE). A person with low activity multiplies by approximately 1.2; someone exercising 3–5 times per week by 1.5–1.7. Perform the full calculation in the TDEE calculator.
Only once you have TDEE can you determine a deficit or surplus — more about this calorie deficit and surplus guides.
⚠️ Calculator Limitations
- The formula does not account for muscle-to-fat ratio — a muscular person's true BMR may be higher.
- The error may reach approximately 10 % — this is a normal feature of this type of calculator.
- Thyroid function, hormones, and illnesses change metabolism, and the formula does not account for it.
- Use the result as a reference point and adjust based on actual weight change.
The best check is to monitor your weight and food intake for two weeks, then adjust.
🧮 When to Recalculate
BMR changes along with body composition and age. It is worth recalculating when your weight changes by several kilograms, after a long diet or mass-gaining phase, and also annually, because metabolism gradually slows with age.
If you follow the plan for several weeks and your weight does not change, the mismatch is most likely not the formula but your activity factor — adjust TDEE, not BMR.