The iPhone in your pocket has been quietly measuring your walking for years — speed, steadiness, symmetry. Export it, drop it here, and read your number, your 6-month trend, and an early flag. Computed entirely on this device. Nothing uploads. Nothing is stored.
On the iPhone (yours, or the parent you're checking on), open the Health app and tap the profile picture, top right.
Scroll down, tap "Export All Health Data," and wait — big exports can take a minute or two to prepare.
Save to Files (or AirDrop it to this device). It's called export.zip — hundreds of MB is normal; this page streams it.
Come back here — on the same phone or any computer — and choose the file. The reading takes seconds.
Everything below runs in your browser — the export is parsed on your device and never transmitted.