Use our Free BMR Calculator to find out how many calories your body burns at rest. This is the number of calories required to maintain basic bodily functions like breathing, circulation, and cell production—also known as your Basal Metabolic Rate (BMR).
BMR Calculator
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What Is BMR?
Basal Metabolic Rate (BMR) is the amount of energy your body needs to perform essential life-sustaining functions while at complete rest and in a fasted, neutrally temperate state.
Think of your BMR as the fuel your body burns just to stay alive—like a car idling in park.
Calculate Your BMR
Try the Free BMR Calculator now:
- Input your age, gender, height, and weight
- Choose your units: US, Metric, or Other
- Adjust settings for advanced formulas like Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle
Why Use a Free BMR Calculator?
Knowing your BMR helps you:
- Set accurate calorie goals
- Avoid over- or under-eating
- Customize fitness and weight loss plans
- Improve long-term health & metabolism
Formulas Used in Our Free BMR Calculator
✅ 1. Mifflin-St Jeor Equation (Most Accurate)
For men: BMR = 10W + 6.25H – 5A + 5
For women: BMR = 10W + 6.25H – 5A – 161
✅ 2. Revised Harris-Benedict Equation
For men: BMR = 13.397W + 4.799H – 5.677A + 88.362
For women: BMR = 9.247W + 3.098H – 4.330A + 447.593
✅ 3. Katch-McArdle Formula (For Leaner Bodies)
BMR = 370 + 21.6 × (1 – F)W
Where:
- W = body weight in kg
- F = body fat %
- H = height in cm
- A = age in years
What Affects Your BMR?
- Age: BMR decreases with age.
- Gender: Males typically have higher BMRs.
- Muscle Mass: More muscle = higher BMR.
- Genetics: Heredity influences metabolic rate.
- Weather: Cold/hot climates increase BMR to regulate body temperature.
- Diet: Starvation reduces BMR; small frequent meals may help increase it.
- Pregnancy & Hormones: Can increase or decrease BMR.
- Supplements: Caffeine and other stimulants can raise BMR.
BMR vs RMR – What’s the Difference?
- BMR (Basal Metabolic Rate): Calculated under strict lab conditions with full rest and fasting.
- RMR (Resting Metabolic Rate): Slightly more flexible, often measured in real-world conditions.
- Both are close in value but not interchangeable in clinical settings.
Limitations of BMR Calculators
Even the most accurate equations are estimates.
There’s still ~26% unknown variance between individuals due to genetics, hormones, and environmental factors. That’s why tracking your progress with a food & fitness journal is key to adjusting your calorie needs over time.
Scientific Reference
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.
Source: American Journal of Clinical Nutrition
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