Resting Metabolic Rate Calculator
Use the scientifically validated Mifflin-St Jeor equation to estimate your resting metabolic rate, the calories your body burns at rest.
The resting metabolic rate (RMR) is the energy your body consumes while at complete rest, supporting breathing, circulation, and intracellular processes. Knowing your RMR helps tailor nutrition plans, set realistic daily calorie targets, and balance energy intake during periods of maintenance, cutting, or bulking.
The Mifflin-St Jeor formula uses your body mass, height, age, and biological sex to estimate this core expenditure. Because muscle and organ tissue consume more energy than fat, leaner individuals typically have a higher RMR. Age also reduces RMR gradually, so older adults need to monitor intake and resistance training to preserve lean mass.
- Weight (kg) reflects the total body mass that needs fueling at rest.
- Height (cm) correlates with larger organ and skeletal demands.
- Age (years) adjusts for hormonal shifts and muscle loss.
- Sex incorporates hormonal differences like testosterone and estrogen.
After computing your RMR, you can layer activity multipliers or track changes from strength-focused diet adjustments. For example, a 70 kg, 175 cm, 30-year-old woman with no training has a lower calorie need than a 90 kg, 185 cm, 35-year-old man, highlighting how personalized RMR beats generic calorie charts.
Interpreting the Result
Once you have your RMR in kcal/day, adjust your daily plan by adding energy from daily activities or reducing calories for a deficit. For example, if you burn 1,600 kcal at rest and lead a sedentary lifestyle, aim for 1,900–2,100 kcal total to maintain weight, factoring in NEAT and intentional movement.
Track your measured weight and body composition over weeks to confirm that this estimate aligns with your actual shifts. If weight changes are slower than desired, double-check your input values for accuracy and consistency.
Use the calculator after major body changes—gaining 5 kg of muscle or losing 8 kg of body fat—which can alter your resting metabolism significantly.