💪 Health & Fitness

BMR Calculator

Calculate basal metabolic rate using Mifflin-St Jeor.

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Calculate basal metabolic rate using Mifflin-St Jeor. This dedicated page is built for fast, clean calculations and search visibility.

Enter your values, click calculate, and see the result instantly. The page uses a simple, focused layout to improve usability on mobile and desktop.

How to use this calculator

  1. Open the bmr calculator page.
  2. Enter the required values in the form fields.
  3. Click Calculate to see the result and breakdown.
  4. Use the related links to explore similar tools.
Results are estimates. For lending, taxes, trading, nutrition, or medical decisions, verify with a qualified professional.

BMR Calculator

Calculate basal metabolic rate using Mifflin-St Jeor.

Result
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    What BMR measures and why it matters

    Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — the energy required for basic survival functions: heartbeat, breathing, maintaining body temperature, and cellular processes. BMR accounts for 60–75% of total daily energy expenditure for sedentary individuals.

    The most commonly used BMR formula is the Mifflin-St Jeor equation: For men: (10 × weight kg) + (6.25 × height cm) – (5 × age) + 5. For women: (10 × weight kg) + (6.25 × height cm) – (5 × age) – 161. This formula is considered more accurate than the older Harris-Benedict equation for modern populations.

    What affects BMR

    • Muscle mass: Each kg of muscle burns approximately 13 kcal/day at rest vs. 4.5 kcal/day for fat. Resistance training is valuable for weight management even beyond direct calorie burn.
    • Age: BMR reduces by approximately 1–2% per decade after age 30.
    • Thyroid function: Hypothyroidism can reduce BMR by 15–40%. Sleep quality and chronic illness also affect BMR significantly outside the standard formula's scope.

    BMR is just the starting calculation; TDEE (BMR × activity factor) is the number that matters for diet planning. To lose weight, eat below TDEE. To gain, eat above TDEE.

    Frequently asked questions

    What is the difference between BMR and RMR?▼
    BMR (Basal Metabolic Rate) is measured under strict conditions — lying still, 12 hours fasted, in a temperature-controlled environment. RMR (Resting Metabolic Rate) is measured at rest but without the strict BMR conditions and is typically 10–20% higher than BMR. In practice, the terms are often used interchangeably, and most calculator formulas calculate RMR while labeling it BMR.
    Does BMR change when I diet?▼
    Yes — prolonged caloric restriction reduces BMR through adaptive thermogenesis. Studies show BMR can decrease 10–15% beyond what weight loss alone would predict. This metabolic adaptation is why long-term dieters sometimes plateau even with continued caloric restriction. Diet breaks (returning to maintenance for 1–2 weeks) can partially reverse this adaptation.
    Can I increase my BMR through exercise?▼
    Resistance training increases lean muscle mass, which raises BMR over time. Building 3–4 kg of muscle (achievable in 1–2 years of consistent training) can increase BMR by 40–50 kcal/day. Cardio exercise doesn't significantly raise BMR but increases TDEE through the activity itself.
    How accurate is the BMR formula?▼
    The Mifflin-St Jeor formula is accurate within ±10% for most individuals. Outliers include athletes (higher BMR due to muscle mass), obese individuals (lower BMR relative to weight due to lower fat metabolic rate), and those with thyroid disorders. For clinical precision, indirect calorimetry (measuring oxygen consumption) is used in medical settings.