Want to understand your body’s energy needs? Our BMR & Calorie Calculator estimates your Basal Metabolic Rate (BMR) and daily calorie requirements based on your age, weight, height, and activity level. Perfect for weight management, fitness goals, and healthy living, this tool delivers accurate, personalized insights to fuel your lifestyle.
A BMR & Calorie Calculator determines your Basal Metabolic Rate—the energy your body uses at rest to maintain vital functions like breathing, heart rate, and brain activity. It adjusts for activity to estimate total daily calorie needs, offering:
BMR accounts for ~70% of daily calorie burn, with ~20% from physical activity and ~10% from digestion (thermogenesis). It’s measured under strict conditions, requiring a fully rested state with an inactive sympathetic nervous system.
The calculator uses the Mifflin-St Jeor equation to compute BMR, then multiplies by an activity factor (1.2–1.9) to estimate total daily energy expenditure (TDEE).
Example:
Female, 25 years, 65 kg, 165 cm, moderately active
BMR: (10 × 65) + (6.25 × 165) - (5 × 25) - 161 = 1,396 kcal
TDEE (Moderate Activity, 1.6 factor): 1,396 × 1.6 ≈ 2,234 kcal
Mifflin-St Jeor Equation:
Men: BMR = 10W + 6.25H - 5A + 5
Women: BMR = 10W + 6.25H - 5A - 161
Revised Harris-Benedict Equation:
Men: BMR = 13.397W + 4.799H - 5.677A + 88.362
Women: BMR = 9.247W + 3.098H - 4.330A + 447.593
Katch-McArdle Formula:
BMR = 370 + 21.6(1 - F)W
Where: W = weight (kg), H = height (cm), A = age, F = body fat (%)
Instantly get:
✔ Your BMR and daily calorie needs
✔ Tailored recommendations for your goals
✔ Tips for diet and exercise optimization
Q1: How accurate is the BMR calculation?
✅ It uses the Mifflin-St Jeor equation, the most reliable formula, though individual factors may cause slight variations.
Q2: Can it help with weight loss?
✅ Yes, it calculates calorie deficits for safe fat loss.
Q3: Does it account for muscle mass?
✅ The Katch-McArdle formula can be used if you know your body fat percentage.
Q4: Why does age affect BMR?
✅ Older age reduces muscle mass, lowering BMR.
Q5: Can I use imperial units?
✅ Yes, input weight in pounds and height in feet/inches.
Your Basal Metabolic Rate (BMR) is the energy required to sustain vital organs—heart, brain, kidneys, liver, lungs, muscles, and more—while at rest in a neutral environment with no digestive activity. Think of it as the fuel an idling car uses. For most, BMR accounts for ~70% of daily energy, with physical activity (~20%) and digestion (~10%, via thermogenesis) making up the rest.
Accurate BMR measurement demands a fully rested state with an inactive sympathetic nervous system. Online calculators estimate BMR using statistical equations, as precise lab tests (e.g., calorimetry) are less accessible. The Mifflin-St Jeor equation, introduced in 1990, is the most accurate, surpassing the revised Harris-Benedict equation. For lean individuals with known body fat percentages, the Katch-McArdle formula, which factors in lean body mass, may offer greater precision.
BMR and RMR are often confused. RMR (Resting Metabolic Rate) measures energy use in a relaxed but not fully rested state, allowing for less strict conditions. BMR requires total physiological equilibrium, making it harder to measure accurately outside labs.
A 2005 study* found a 26% unexplained variance in BMR even after controlling for factors like fat-free mass and age. This means calculations, even with precise methods, are estimates. For best results, combine BMR/TDEE estimates with a journal tracking exercise, diet, and progress to identify what works for your body.
* Johnstone AM, Murison SD, Duncan JS, Rance KA, Speakman JR, Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. Am J Clin Nutr 2005; 82: 941-948.
Knowing your BMR and calorie needs is essential for weight management, fitness, and overall health. Our Free Online BMR & Calorie Calculator provides reliable, science-backed estimates to guide your nutrition and exercise plans.
🚀 Start optimizing your health today!
This content for the BMR & Calorie Calculator is independently researched and authored by me, based on nutritional science and metabolic calculation principles.
Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic functions like breathing, circulation, and cell production while at complete rest.
Formula (Mifflin-St Jeor):
For men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) + 5
For women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) − 161