BMR & TDEE Calculator
Your basal metabolic rate is what you burn doing nothing at all. Multiply it by how much you move and you get your total daily energy expenditure, which is the number that actually matters for eating.
Enter your age, height and weight to see what you burn.
Mifflin-St Jeor, then an activity multiplier.
BMR here uses the Mifflin-St Jeor equation, which has held up better against measured metabolic rates than the older Harris-Benedict formula. For reference the page shows the revised Harris-Benedict number as well, so you can see the size of the disagreement rather than trusting one line.
TDEE is BMR multiplied by an activity factor between 1.2 and 1.9. These factors are broad brackets, not measurements, and the gap between two neighbouring rungs is often several hundred calories. Pick the one that matches a normal week rather than your best one.
Treat the result as a starting point. Eat at it for a fortnight, weigh yourself under the same conditions, and adjust from what actually happened. No equation knows your NEAT, your sleep or how hard you really train.
Numbers are the easy part.
Rubber Bands turns a goal into a schedule you can actually keep, built around the resistance bands you already own.