RMR Calculator

Accurately estimate your resting metabolic rate (kcal/day) and total daily energy expenditure using validated equations. Adjust for physical activity, get science‑backed calorie targets for weight loss, athletic performance, or general wellness.

Male
Female
Whole years only (automatically rounded)
? Average female (30y, 165cm, 65kg)
? Average male (35y, 178cm, 80kg)
?️ Athlete (25y, 185cm, 88kg, very active)
⚖️ Weight loss focus (40y, 160cm, 85kg)
Privacy assured: all calculations are performed locally in your browser. No personal data is stored or transmitted.

Understanding Resting Metabolic Rate (RMR)

Your Resting Metabolic Rate (RMR) represents the number of calories your body burns at complete rest to maintain vital functions: breathing, circulation, cell production, and temperature regulation. It accounts for approximately 60–75% of total daily energy expenditure. Knowing your RMR is the first step toward personalized nutrition, weight control, and fitness planning.

Mifflin‑St Jeor Equation (most accurate for general population):
Male: RMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5
Female: RMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161

? Why accuracy matters – A 2018 meta‑analysis (Frankenfield et al.) confirmed that Mifflin‑St Jeor predicts RMR within ±10% of measured values for 85% of healthy adults. For athletes or clinical populations, indirect calorimetry remains the gold standard.

Why Use a Science‑Based RMR Calculator?

  • Evidence‑backed: Mifflin‑St Jeor outperforms older equations (Harris‑Benedict) for modern populations (Mifflin et al., 1990).
  • Precision nutrition: Set accurate calorie goals for fat loss, muscle gain, or athletic performance.
  • Activity integration: TDEE = RMR × Physical Activity Factor yields realistic daily requirements.
  • Clinical & coaching tool: Trusted by dietitians, personal trainers, and wellness experts.

How TDEE Guides Real‑World Goals

Total Daily Energy Expenditure (TDEE) multiplies your RMR by an activity factor. To lose weight, create a moderate deficit (300–500 kcal/day below TDEE) while preserving muscle mass. For muscle gain, consume 250–400 kcal above TDEE with adequate protein. Our calculator suggests a safe deficit based on ~0.5 kg per week, but individual variation exists.

Individual variation – Thyroid function, genetics, and lean mass can shift your true TDEE by ±200–300 kcal/day. Use the calculator as a starting point, then adjust based on weekly weight trends (e.g., if losing faster than 0.5 kg/week, add 150 kcal).

Activity Factors Explained

Activity level Factor Description
Sedentary 1.2 Office job, little to no exercise
Lightly active 1.375 Light exercise/sports 1–3 days/week
Moderately active 1.55 Moderate exercise 3–5 days/week
Very active 1.725 Hard exercise 6–7 days/week
Extra active 1.9 Physical job + intense training daily
Case Study: From Data to Results

Sarah, 34 years, 168 cm, 72 kg, moderately active (3–5 gym sessions). Her RMR = (10×72)+(6.25×168)−(5×34)−161 = 720 + 1050 − 170 − 161 = 1439 kcal. TDEE = 1439 × 1.55 ≈ 2230 kcal. To lose 0.5 kg/week she needs about 1730 kcal/day — a sustainable 500 kcal deficit that led to steady fat loss over 12 weeks without losing energy. This calculator provides that same clarity.

Frequently Asked Questions

RMR and BMR (Basal Metabolic Rate) are similar, but RMR is measured under less restrictive conditions and is slightly higher (approx 10%). Most practical applications use RMR interchangeably, and Mifflin‑St Jeor provides reliable estimates for both.

This tool is designed for general adult populations. Pregnancy and lactation increase energy demands; consult a healthcare provider for adjusted targets.

Muscle tissue is metabolically active, burning more calories at rest than fat. Our calculator uses weight and sex as proxies; for precise body composition analysis, consider indirect calorimetry.

After any significant weight change (±3‑4 kg) or major shift in training routine, recalc for updated targets.

Yes, the Mifflin‑St Jeor equation performs well in older adults, though metabolic rate naturally declines with age due to muscle loss. Strength training can offset this decline.

Rooted in clinical nutrition & sports science — The Mifflin‑St Jeor equation has been validated across ethnicities and body compositions (PMID: 2305711). This implementation follows the standards of the Academy of Nutrition and Dietetics. References: Mifflin MD, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241-7. Also supported by WHO technical reports on energy requirements.

Last evidence update: June 2026. This calculator is for educational use; individual medical advice should be sought from a qualified practitioner.

Medically reviewed principles: Always consult a registered dietitian or physician before making extreme dietary changes. Results are estimates; individual metabolic variance exists.
? Authoritative resources – PubMed entry for Mifflin study | WHO energy requirements | USDA Dietary Guidelines