Your Basal Metabolic Rate (BMR) is the number of calories your body would burn if you rested in bed all day. It is the largest single component of most people's daily energy expenditure. This calculator uses the Mifflin-St Jeor equation — the modern standard for estimating BMR.
Your estimated BMR
1,618
kcal / day
This is the energy your body would use at complete rest in a fasted, thermo-neutral state (Mifflin-St Jeor equation). Add activity and digestion to get your actual daily burn — see the TDEE calorie calculator.
BMR is not the same as the calories you "should eat." It is purely the energy required to keep your heart beating, lungs breathing, body warm, and cells working when you are completely at rest and in a fasted state. Real daily burn is BMR plus activity, digestion, and movement — see our calorie (TDEE) calculator for that combined figure.
For adults the formula used here is:
It replaced the older Harris-Benedict equations because it is more accurate on average, especially for people whose actual body composition differs from older reference populations. Even so, BMR is an estimate and varies between individuals by roughly 5–10%.
Knowing your BMR gives you a floor for safe eating: diets that drop intake dramatically below BMR for long periods tend to lose lean mass and can reduce metabolic rate. For sustainable fat loss, start from BMR, add activity (the TDEE multiplier), and create a modest deficit of around 500 kcal/day. Combine with our BMI calculator and ideal weight calculator for context, and consult a registered dietitian if you have a medical goal.