Health & Fitness
BMR Calculator
Estimate resting calories and activity-adjusted TDEE from common formulas.
Result
Enter your numbers and press Calculate to see the result.
Calculating…
How BMR is calculated
Basal metabolic rate is the energy your body burns at complete rest. This calculator supports the three most-used equations: Mifflin-St Jeor (the modern default), the revised Harris-Benedict, and Katch-McArdle for people who know their body fat percentage. Imperial units are converted to metric automatically.
Formulas
Mifflin-St Jeor (men): 10 × kg + 6.25 × cm − 5 × age + 5
Mifflin-St Jeor (women): 10 × kg + 6.25 × cm − 5 × age − 161
Harris-Benedict (men): 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age
Harris-Benedict (women): 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age
Katch-McArdle: 370 + 21.6 × lean mass (kg)
Worked example
A 30-year-old woman, 70 kg, 170 cm, with Mifflin-St Jeor: 10 × 70 + 6.25 × 170 − 5 × 30 − 161 = 700 + 1,062.5 − 150 − 161 = ≈ 1,452 kcal/day. That is roughly 10,160 kcal per week just to keep the body running at rest.
Which formula should you use?
Mifflin-St Jeor is the modern default and the most accurate for the general population, so use it unless you have a reason not to. Harris-Benedict is the older equation, kept here for comparison and for anyone whose plan or coach references it. Katch-McArdle can be more accurate for lean, muscular people because it works from lean body mass instead of total weight — but it only helps if you have a reliable body-fat measurement, since a rough guess feeds a rough result.
BMR, RMR, and your real burn
BMR is measured under strict resting conditions; resting metabolic rate (RMR) is a slightly looser, higher figure you will often see used interchangeably. Either way, this is only the energy to keep you alive at rest — it excludes walking, exercise, and even digesting food. Your actual daily burn is BMR multiplied by an activity factor, which is exactly what the calorie calculator does next.
BMR is only the baseline — to turn it into a daily calorie target that accounts for activity and your goal, use the calorie calculator.
BMR Calculator — frequently asked questions
What is BMR?
Basal metabolic rate is the energy your body burns at complete rest just to keep vital functions running — breathing, circulation, cell repair. It is the baseline that activity calories are added on top of.
Which BMR formula is most accurate?
For most people the Mifflin-St Jeor equation (the default here) is considered the most reliable modern estimate. The revised Harris-Benedict is an older alternative that tends to run slightly higher.
When should I use Katch-McArdle?
Use it if you know your body fat percentage. Katch-McArdle estimates BMR from lean body mass (370 + 21.6 × lean kg), which makes it more accurate for very muscular or very lean people.
What is the difference between BMR and TDEE?
BMR is energy burned at rest; TDEE (total daily energy expenditure) is BMR multiplied by an activity factor to account for movement and exercise. Use our calorie calculator to get TDEE and a daily calorie target.