Resting Metabolic Rate (RMR) Calculator
Calculate your RMR using the Mifflin-St Jeor equation, the most accurate prediction formula recommended by the Academy of Nutrition and Dietetics. RMR accounts for 60-70% of daily calorie expenditure.
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⚠️For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.
RMR (Resting Metabolic Rate) is the calories your body burns at complete rest. The Mifflin-St Jeor equation is the gold standard, recommended by the Academy of Nutrition and Dietetics. RMR accounts for 60-70% of daily calorie expenditure. Accuracy is typically ±10%.
Sources: Mifflin-St Jeor (1990), Academy of Nutrition and Dietetics.
Key Takeaways
- • Mifflin-St Jeor is the most accurate formula for most adults
- • RMR accounts for 60-70% of total daily expenditure
- • Katch-McArdle is better when body fat % is known
- • Metabolic rate declines ~1-2% per decade after age 30
Did You Know?
How Does RMR Work?
Mifflin-St Jeor
Men: (10×weight) + (6.25×height) - (5×age) + 5. Women: (10×weight) + (6.25×height) - (5×age) - 161. Weight in kg, height in cm.
Katch-McArdle
RMR = 370 + (21.6 × lean body mass in kg). Best when body fat % is known.
TDEE Estimate
TDEE ≈ RMR × Activity Factor (1.2 sedentary to 2.1 athlete).
Expert Tips
Formula Comparison
| Formula | Best For | Inputs |
|---|---|---|
| Mifflin-St Jeor | General population | Weight, height, age, gender |
| Harris-Benedict | Traditional | Weight, height, age, gender |
| Katch-McArdle | Known body fat | Lean mass or weight + BF% |
Frequently Asked Questions
What is RMR?
Resting Metabolic Rate (RMR) is the calories your body burns at complete rest for vital functions. It accounts for 60-70% of total daily energy expenditure. RMR and BMR are often used interchangeably.
Which RMR formula is most accurate?
Mifflin-St Jeor is the gold standard recommended by the Academy of Nutrition and Dietetics. It's typically within ±10% of measured RMR for most adults. Katch-McArdle is better when body fat % is known.
How does RMR differ from BMR?
RMR and BMR are nearly identical. RMR is measured under less strict conditions (e.g., after a light meal) and is typically 10% higher. For practical purposes, they're used interchangeably.
What affects my metabolic rate?
Age, gender, body composition, genetics, thyroid function, diet history, and muscle mass all influence RMR. Muscle is more metabolically active than fat.
Can I increase my RMR?
Building lean muscle through resistance training, adequate protein intake, and avoiding severe calorie restriction can help. Severe dieting may lower RMR by 15-20% (adaptive thermogenesis).
How often should I recalculate RMR?
Recalculate when weight changes by 5+ lbs, body composition changes significantly, or every 3-6 months. Age-related decline is ~1-2% per decade after 30.
Key Statistics
Official Data Sources
⚠️ Disclaimer: This calculator is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider or registered dietitian. Not medical advice.