BMR Calculator

How to use it

Enter your height, weight, age, and sex, then choose the activity level that best matches your week. The calculator returns two numbers: your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest just to keep organs running — and your Total Daily Energy Expenditure (TDEE), which scales BMR up for the calories you burn through movement and exercise. BMR is estimated with the Mifflin-St Jeor equation, generally considered one of the more accurate formulas for resting metabolic rate. For men: 10 × weight in kg + 6.25 × height in cm − 5 × age in years + 5. For women, the constant changes: 10 × weight in kg + 6.25 × height in cm − 5 × age in years − 161. For example, a 30-year-old man who is 180 cm tall and weighs 80 kg has a BMR of (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1125 − 150 + 5 = 1780 kcal/day. If he's moderately active (exercising 3–5 days a week), TDEE multiplies BMR by an activity factor of about 1.55: 1780 × 1.55 ≈ 2759 kcal/day — roughly what he'd need to eat to maintain his current weight. Activity factors range from 1.2 for sedentary (desk job, little to no exercise) up to 1.725 for very active (hard daily training or a physically demanding job) — the more you move, the higher the multiplier, and the more calories TDEE adds on top of BMR. These numbers are estimates, not lab measurements. The Mifflin-St Jeor equation was derived from population averages and can be off by 10% or more for any individual, especially people with unusually high muscle mass, very low body fat, or a medical condition affecting metabolism. Use TDEE as a starting point for planning calorie intake — eat somewhat below it to lose weight, somewhat above it to gain — and adjust based on how your actual weight changes over a few weeks. For clinical accuracy, or if you have a health condition affecting metabolism, talk to a doctor or dietitian rather than relying on an online estimate alone.

Frequently asked questions

What is the difference between BMR and TDEE?

BMR is the calories you'd burn at complete rest. TDEE is BMR scaled up for your daily activity — a better estimate of how much you actually need.

Which formula is used?

The Mifflin-St Jeor equation, widely considered one of the most accurate for estimating resting metabolic rate.

How accurate is the Mifflin-St Jeor equation?

It's considered one of the more reliable predictive equations for resting metabolic rate, but it's still a population-based estimate — actual BMR can vary by 10% or more depending on muscle mass, genetics, and health conditions. Use it as a starting point, then adjust based on real-world weight changes over time.

Which activity level should I choose?

Pick the option closest to your typical week, not your best week. Sedentary means a desk job with little deliberate exercise; light is 1–3 workouts a week; moderate is 3–5; active is 6–7; very active means daily hard training or a physically demanding job. If unsure, choose the lower option.