Calorie math, done properly.

Start with the number every plan is built on — your TDEE. Mifflin-St Jeor equation, documented constants, no signup, no email gate.

Sex

Age

Height

Weight (lb)

Activity level

Body fat % (optional)

Formula: Mifflin-St Jeor (Katch-McArdle when body fat % is given) × activity factor. Every constant is documented on the methodology page. Educational estimate — not medical advice.

All five calculators

TDEE CalculatorHow many calories you burn per day, from the Mifflin-St Jeor equation and your activity level.Macro CalculatorDaily protein, carb and fat grams for your goal — cut, maintain or lean bulk.Protein CalculatorYour daily protein target in grams, from RDA baseline to training and cutting ranges.Calorie Deficit CalculatorPick a −10%, −20% or −25% deficit from your TDEE, with expected weekly loss.Maintenance Calorie CalculatorThe daily calories that hold your weight steady — the anchor number every plan starts from.

Which one do I start with?

Start with TDEE — everything else is arithmetic on top of it. Losing weight? Take your TDEE into the deficit calculator, then structure the target with macros. Holding steady? That is the maintenance calculator. And whatever the goal, the protein calculator tells you the one macro worth anchoring first.

Why trust these numbers?

Because none of them are ours. BMR comes from the Mifflin-St Jeor equation (1990), the most validated of the common predictive formulas; activity factors are the standard 1.2–1.9 multipliers; protein ranges follow the ISSN position stand and published reviews for dieting athletes. Where you know your body fat percentage, we switch to Katch-McArdle. The full list of constants and citations lives on the methodology page — if a number on this site can't be traced to a source, it doesn't ship.