How to Calculate Basal Metabolic Rate
Basal metabolic rate (BMR) is the number of calories your body needs to maintain vital functions such as breathing, circulation, and cell repair while you are at complete rest. Unlike total daily energy expenditure, BMR excludes exercise and general movement, so it is the first anchor point for a sustainable nutrition plan.
The most reliable way to calculate BMR is to feed your weight, height, age, and biological sex into the Mifflin-St Jeor equation. The equation returns your resting calorie burn, which you can then layer with activity multipliers for a more comprehensive plan.
Your lean mass has the biggest influence on BMR. Every additional kilogram adds roughly 10 calories to the resting total.
Taller bodies require more energy to circulate blood and regulate temperature, so the formula credits about 6.25 calories per centimeter.
Age subtracts 5 calories per year, and the equation adds +5 for males and -161 for females to account for average hormonal differences.
Basal Metabolic Rate Calculator
Enter your current measurements below. This calculator reports calories burned at rest, so avoid including a workout right before taking your baseline.
The formula used is 10 × weight (kg) + 6.25 × height (cm) – 5 × age (years) + sex modifier. That modifier is +5 for males and -161 for females, creating a precise baseline for each physiology.
Real-Life Examples
Example: A 38-year-old woman who is 62 kilograms and 165 centimeters tall has a BMR of 10 × 62 + 6.25 × 165 – 5 × 38 – 161 = 1,315 kcal/day. That is the minimal energy needed to maintain her organs while she rests in a quiet room.
Example: A 44-year-old man weighing 86 kilograms at 183 centimeters tall reaches 10 × 86 + 6.25 × 183 – 5 × 44 + 5 = 1,789 kcal/day. Use that number as the lowest boundary before adding calories burned through commuting, standing, cleaning, or training.
These realistic figures show how much weight and height shift the resting total, so you can compare different body compositions without guessing.
Applying Your Basal Metabolic Rate
- Record your BMR when you are fully rested; avoid days with fever or prolonged travel, as those stresses raise your metabolism temporarily.
- Layer an activity multiplier (1.2 for sedentary, 1.35 for lightly active, etc.) on top of the BMR to estimate maintenance calories.
- If you plan a deficit or surplus for fat loss or muscle gain, subtract or add 10-20% of the BMR before adjusting macros.
Tracking this number every few months helps you spot metabolic adaptions as you lose fat or gain muscle.