🔥 BMR Calculator
Calculate your Basal Metabolic Rate (BMR) and daily calorie needs (TDEE) based on your stats and activity level.
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BMR and TDEE — The Numbers Behind Your Calorie Needs
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — the energy required simply to keep you alive: breathing, circulation, maintaining body temperature, and cellular function. It's what you'd burn if you stayed completely still and awake for 24 hours. BMR accounts for approximately 60–75% of total daily energy expenditure for most sedentary people.
Total Daily Energy Expenditure (TDEE) = BMR × Activity Multiplier. The multipliers used in this calculator are: sedentary (desk job, no exercise) ×1.2; lightly active (exercise 1–3 days per week) ×1.375; moderately active (exercise 3–5 days per week) ×1.55; very active (hard exercise 6–7 days per week) ×1.725; extra active (very hard exercise or physical job plus training twice daily) ×1.9. The "exercise" in these descriptions means structured physical activity — walking to and from work counts, but less so than dedicated gym sessions.
Most people overestimate their activity level. Someone who sits at a desk 9 hours per day and does a 30-minute jog four times per week is lightly to moderately active at best — not "very active." Choosing the activity multiplier honestly is important because overestimating it leads to overestimating TDEE and unintentionally eating at a surplus when you believe you're in a deficit.
The Mifflin-St Jeor equation used here is: BMR (men) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. BMR (women) = 10 × weight + 6.25 × height − 5 × age − 161. It's considered the most accurate of the commonly available formulas for typical adults. The Harris-Benedict equation (the original, from 1919) tends to overestimate by 5–10% for modern sedentary populations.
BMR decreases with age (roughly 1–2% per decade) as muscle mass naturally decreases with aging. This is one reason why maintaining muscle mass through resistance training as you age is important for metabolic health — more muscle means a higher BMR and less propensity for body fat accumulation as calorie needs decline with age.
What Is BMR and How Is It Calculated?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep basic functions running: breathing, circulation, cell repair, and temperature regulation. It represents the minimum energy your body needs to survive.
Your BMR is calculated using the Mifflin-St Jeor equation, the most widely validated formula: For men: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. For women: (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161. Multiply by an activity factor to get your total daily energy expenditure (TDEE).