Calorie calculator

Mifflin-St Jeor for resting energy: 10 × weight in kg + 6.25 × height in cm − 5 × age, plus 5 for men and minus 161 for women. It predicts resting energy more accurately than Harris-Benedict across the general population, which is why it is the one used. That figure is then multiplied by an activity factor between 1.2 and 1.9 to get maintenance.

Because a constant is a different job for different bodies. 500 kcal is about 29% of a small athlete's intake and only about 16% of a large one's, so it is too deep to sustain at one end and too shallow to progress at the other. Panko targets a weekly rate of bodyweight change instead, so the deficit scales with you.

Fat loss runs at 0.7% of bodyweight a week, capped at 1 kg. Lean gaining runs at 0.35% a week and deliberate weight gain at 0.6%, both capped at 0.5 kg, because tissue can only be built so fast and a faster climb is mostly fat.

No. A deficit is never deeper than 25% under maintenance, a surplus never higher than 20% over it, and intake never drops below 1,500 kcal for men or 1,200 for women. If a rail bites, the tool says so.

Yes. The app derives your daily target from the same formulas and the same rails, then re-derives it every time you log a new bodyweight.