BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at complete rest. The foundation of any nutrition or weight management plan.
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What is BMR?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions while at complete rest — breathing, circulation, cell production, and temperature regulation.
It represents the minimum energy your body needs to survive if you did nothing but lie in bed all day. Understanding your BMR is the first step to:
- 🎯 Setting accurate calorie goals for weight loss or gain
- 💪 Planning an effective fitness nutrition strategy
- 📊 Understanding your metabolic health
Which formula to choose? The Mifflin-St Jeor formula is the most accurate for most people. The Katch-McArdle formula is best if you know your body fat percentage (e.g. from a DEXA scan).
What Is BMR and Why Does It Matter?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic vital functions — breathing, blood circulation, cell repair, temperature regulation, and organ function. BMR represents the minimum energy your body needs to survive if you stayed in bed all day.
BMR typically accounts for 60–75% of total daily calorie expenditure, making it by far the largest component of your metabolism. Understanding your BMR helps you set realistic calorie targets for weight management and makes sense of why two people of similar weight can have very different metabolic rates.
How Is BMR Calculated?
Our BMR Calculator uses the Mifflin-St Jeor Equation (1990), which is the most accurate formula for the general population according to research:
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
We also offer the Harris-Benedict Equation (1919, revised 1984) as an alternative:
- Men: BMR = 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age)
- Women: BMR = 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)
Factors That Affect BMR
BMR is not fixed — it changes with several factors:
- Age: BMR decreases approximately 1–2% per decade after age 20 due to muscle loss (sarcopenia)
- Sex: Men have higher BMR than women due to greater muscle mass and lower body fat percentage
- Body composition: Muscle tissue burns ~6 calories/pound at rest; fat tissue burns ~2 calories/pound — highly muscular people have higher BMR
- Hormones: Thyroid hormones (T3/T4) are the primary regulators of metabolic rate
- Temperature: BMR increases in cold environments (thermogenesis) and during fever
BMR vs RMR — What’s the Difference?
Resting Metabolic Rate (RMR) is often used interchangeably with BMR but is slightly higher (typically 10–20% more) because it’s measured under less strict conditions — seated, after a 4-hour fast, rather than completely at rest after 12+ hours of fasting. Most online “BMR calculators” actually estimate RMR.
How to Use Your BMR
BMR is the starting point for calculating your TDEE (Total Daily Energy Expenditure) — the total calories you burn including activity. Multiply your BMR by your activity factor to get your maintenance calories. From there, subtract or add calories based on whether you want to lose or gain weight.
Can You Increase Your BMR?
Yes — the most effective strategies are:
- Build muscle mass through resistance training (the single biggest lever)
- Avoid extreme calorie restriction which triggers metabolic adaptation (starvation mode)
- Eat adequate protein — the thermic effect of protein is 20–30% vs 5–10% for carbs
- Stay consistent with training even during weight loss phases