The treadmill says zero.
Your legs disagree.

Stepper Pro exists because gym treadmills are bad at counting, and the alternatives wanted my life story first.

Walking on a treadmill is the one kind of walking where your body barely moves through space. The belt goes backward, you stay put — and that is exactly the pattern most step counters are built to ignore. They are tuned to be conservative outdoors, so they filter out the steady, uniform gait of a treadmill and quietly undercount it. Meanwhile every fitness app I tried wanted an account, an email, a subscription, and permission to sync my movement to somebody else's server.

So I wrote the counter I wanted: it assumes that when you press play, you are walking, and then it counts your gait honestly. It runs entirely on the phone in your pocket. There is no account, no server, and nothing to cancel — because there is nothing to sell.