BMR Calculator

BMR is the amount of energy (calories) your body burns at rest to maintain basic life functions like breathing, circulation, cell production, nutrient processing, protein synthesis, and ion transport. It represents the minimum number of calories needed to keep your body functioning while at complete rest.

The Mifflin-St Jeor equation is recommended for most people as it's the most accurate. The Harris-Benedict equation is the traditional formula but slightly less accurate. The Katch-McArdle formula is most accurate for lean individuals who know their body fat percentage.

BMR calculations are estimates based on statistical data. Even the most precise methods have limitations, and individual variations can be up to 26% due to factors like genetics, muscle mass, and metabolic conditions. For the most accurate results, consider consulting a healthcare professional or using specialized equipment.

Activity multipliers estimate your total daily energy expenditure (TDEE): Sedentary (1.2x) - little or no exercise; Light (1.375x) - exercise 1-3 times/week; Moderate (1.55x) - exercise 4-5 times/week; Active (1.725x) - daily exercise or intense exercise 3-4 times/week; Very Active (1.9x) - intense exercise 6-7 times/week; Extra Active (2.1x) - very intense exercise daily or physical job.

BMR typically decreases with age due to loss of muscle mass and changes in body composition. This is why the formulas include age as a factor - older individuals generally have lower metabolic rates than younger people with similar body compositions.

Men typically have higher BMR than women due to generally higher muscle mass and different body composition. The formulas account for these biological differences to provide more accurate estimates for each gender.

Muscle tissue is more metabolically active than fat tissue, so individuals with higher muscle mass and lower body fat typically have higher BMR. The Katch-McArdle formula specifically accounts for this by using lean body mass in its calculation.

Yes, BMR is the foundation for weight loss planning. To lose weight, you need to consume fewer calories than your TDEE (BMR × activity multiplier). A safe deficit is typically 500-1000 calories per day, which can result in 1-2 pounds of weight loss per week.

Several factors can affect your actual BMR: muscle mass (more muscle = higher BMR), genetics, thyroid function, body temperature, stress levels, pregnancy, certain medications, and extreme dieting (which can lower BMR).

Recalculate your BMR when there are significant changes in your weight, body composition, age, or activity level. For most people, recalculating every 3-6 months or after significant weight changes is sufficient.