RMR Calculator (Katch-McArdle Formula)
Enter your total body weight and body fat percentage to estimate your Resting Metabolic Rate.
RMR Calculator (Katch-McArdle Formula)
Estimate your Resting Metabolic Rate using the Katch-McArdle formula, based on lean body mass.
Unlike formulas that use total body weight, age and sex, the Katch-McArdle formula estimates RMR from lean body mass alone — often considered more accurate for people who know their body fat percentage, especially those who are more muscular or leaner than average.
Example
- With the default values shown above, this calculator returns: Lean Body Mass (kg) ≈ 60.0; Resting Metabolic Rate (kcal/day) ≈ 1,666.
Frequently Asked Questions
How is this different from BMR calculators using age and sex?
Formulas like Mifflin-St Jeor use total weight, height, age and sex as proxies for body composition; Katch-McArdle instead uses your actual lean body mass directly, which can be more accurate if you know your body fat percentage.
Is RMR the same as calories I should eat?
No — RMR is roughly the energy your body uses at complete rest. Your total daily calorie needs are higher once activity is factored in.