Free, no account, nothing stored. Each one is the standard equation for the job, shown with the arithmetic it uses and the point at which it stops being able to tell you anything.
Every calculator on this page works the same way: it takes your height, your weight, your age and a guess about how much you move, and returns the average answer for people who look like that on paper. It is a reasonable place to start. It is not a reading of you, and it cannot change when you do.
Rysflo measures instead. One sixty-second exhale each morning reads three molecules in your breath, and the day’s protein, carbohydrate, fat and fibre come out in grams — against the goal you set, from what your metabolism is actually doing rather than from a formula on your dimensions.