BMR
CALCULATOR
Find the calories your body burns at complete rest — the foundation of all nutrition planning.
What This Calculator Does
The BMR Calculator computes your Basal Metabolic Rate — the calories your body burns at complete rest to maintain vital functions. It shows both Mifflin-St Jeor (most accurate) and Harris-Benedict results, plus activity-adjusted TDEE estimates.
The Formula Explained
Mifflin-St Jeor (men): BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5. Mifflin-St Jeor (women): same but −161. Example: 30-year-old female, 165cm, 65kg → BMR = (650 + 1,031 − 150 − 161) = 1,370 kcal/day at complete rest.
What Your Result Means
BMR represents 60–70% of your TDEE. Muscle mass is one of the primary drivers of BMR — each kg of lean muscle is estimated to burn roughly 13 kcal/day at rest, compared to about 4.5 kcal/day for a kg of fat tissue. This is one reason resistance training that builds or preserves muscle tends to support a higher resting metabolism over time, though individual results vary. Your BMR tends to decline roughly 1–2% per decade after 30, partly due to age-related muscle loss, unless you actively work to preserve muscle mass.
TDEE Calculator to add your activity level · Calorie Calculator for goal-specific targets
What Is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic physiological functions: breathing, circulation, cell production, and body temperature regulation. BMR typically represents 60 to 70 percent of total daily calorie expenditure and is the foundational number behind all nutrition and energy calculations.
Mifflin-St Jeor vs Harris-Benedict
The Mifflin-St Jeor equation (1990) is the most accurate formula for most people and is recommended by the American Dietetic Association. It outperforms the older Harris-Benedict equation (1919) by approximately 5% in studies comparing predicted vs measured metabolic rate. However, neither formula accounts for lean body mass, which is why the Katch-McArdle formula (using body fat percentage) is more accurate for very lean or very muscular individuals.
BMR vs TDEE
BMR is your resting calorie burn. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor — your real-world daily calorie burn. Multiply your BMR by 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active, and 1.9 for extremely active individuals.