BMR Calculator
Calculate your basal metabolic rate with Mifflin-St Jeor, revised Harris-Benedict or Katch-McArdle, and see calories burned at each activity level.
Results
Calories by activity level
| Activity level | Multiplier | kcal |
|---|---|---|
| Sedentary (little or no exercise) | 1.2 | 2,136 |
| Lightly active (1–3 days/week) | 1.375 | 2,448 |
| Moderately active (3–5 days/week) | 1.55 | 2,759 |
| Very active (hard exercise 6–7 days/week) | 1.725 | 3,071 |
| Extra active (physical job + training) | 1.9 | 3,382 |
- Mifflin-St Jeor: 10·kg + 6.25·cm − 5·age + 5 (men) or − 161 (women). Katch-McArdle: 370 + 21.6 × lean mass (kg).
What is BMR Calculator?
Calculates your basal metabolic rate – the energy your body uses at complete rest – with three established equations side by side, and shows the corresponding daily calories for five activity levels.
How to use BMR Calculator
- Choose units and enter Sex, Age, Weight and Height.
- Choose the Formula; for Katch-McArdle also enter your Body fat percentage.
- Read your BMR in kcal (and kJ), the results of the other formulas and the activity table.
Example
Male, 30 years, 80 kg, 180 cm, Mifflin-St Jeor
BMR 1,780 kcal/day (7,448 kJ); Harris-Benedict 1,854 kcal
When to use BMR Calculator
Use it to understand your baseline energy needs or as input to a diet plan. BMR is an estimate; indirect calorimetry is needed for an exact measurement.
How BMR Calculator works
Mifflin-St Jeor (1990): 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women). Revised Harris-Benedict (Roza & Shizgal, 1984): men 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age; women 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age. Katch-McArdle: 370 + 21.6 × lean body mass (kg), where lean mass = weight × (1 − body fat %). The activity table multiplies BMR by 1.2, 1.375, 1.55, 1.725 and 1.9.
Common Use Cases
- Comparing BMR formulas
- Getting the base number for TDEE
- Checking the effect of weight loss on BMR
- Nutrition coursework
FAQs
What is the difference between BMR and RMR?
BMR is measured under stricter conditions (fasting, fully rested); RMR is slightly higher. Calculators usually estimate both with the same equations.
Why do the formulas give different results?
They were fitted to different study populations and decades. Differences of 50–100 kcal are normal.
When should I use Katch-McArdle?
When you have a reliable body fat measurement, especially if you are very muscular or have high body fat.