Free health calculators

Turn your Apple Watch numbers into answers. Free, no sign-up.

How old your body is, from the numbers your Apple Watch already tracks.

Your five training zones in beats per minute, with Zone 2 up front.

The best times to go to bed or wake up, in whole sleep cycles.

Your last coffee before bed, and how much caffeine is left at lights out.

How your HRV ranks for your age and sex, with your HRV age.

How your VO2 max ranks for your age and sex, with your fitness age.