Free tools
Free tools, no sign-up, nothing sent anywhere
Small, precise calculators for the numbers that actually change training decisions. They run entirely in your browser, so nothing you type ever leaves your device.
Heart rate zone calculator
Work out your five training heart rate zones from your age or measured maximum. Free, instant, and runs entirely in your browser with…
Open the tool →Sleep debt calculator
Enter your last seven nights and your nightly need to see your running sleep debt, how many nights were short, and how long it will take to…
Open the tool →Maximum heart rate calculator
Compare four validated maximum heart rate formulas side by side, including Tanaka and the women-specific Gulati equation, and understand…
Open the tool →Free, and free of the usual strings
These calculators require no account, no email address, and no payment. They carry no advertising and set no tracking cookies. Every one of them runs as JavaScript inside your browser, which means the numbers you type are never transmitted anywhere, including to us.
You can verify that claim yourself: load a tool, disconnect from the internet, and it will keep working.
They exist because the same arithmetic sits inside Apex Health: Recovery Coach, and there is no good reason to hide it behind an app download.
Wake up to a verdict, not a spreadsheet.
Apex Health: Recovery Coach turns the Apple Health data you already generate into one clear decision each morning. Free, private, and entirely on your device.
Apex Health: Recovery Coach provides general wellness and fitness information computed from your own data. It is not a medical device and does not diagnose, treat, or prevent any condition. Always consult a qualified professional for medical concerns.