AltLog: Altimeter & Elevation

A simple altitude logger that uses the iPhone's pressure sensor — no GPS. Tap Start before a climb. See ascent, descent, and stair-equivalents tallied live.

AltLog is a one-tap elevation logger. It reads the barometric pressure sensor built into your iPhone — the same chip that powers Apple's Floors Climbed metric — and turns it into a live tally of metres climbed, metres descended, and stair-equivalents.

There is no GPS. None. AltLog never asks for your location, and battery cost is negligible. The pressure sensor sips power compared to GPS, so a long city walk costs you a single-digit percentage of battery.

WHEN IT WORKS • Inside parking garages, multi-story buildings, and stairwells where GPS is useless. • On hiking trails when you want a low-power supplement to your map app. • In elevators — yes, you can verify the "23rd floor" sign matches what the sensor saw. • Anywhere there is air. (Sealed pressurised vehicles excepted — physics, not us.)

HOW TO USE

1. Tap Start before a walk, hike, or staircase climb.
2. Watch the ascent and descent tally update every second.
3. Tap Stop when you're done. The session lands in History with an altitude profile.
4. Add the Today Ascent widget to your Home Screen for at-a-glance totals.
5. Glance at the wrist — the standalone Apple Watch app runs a session without your phone.

WHAT YOU GET • Live cumulative ascent in metres and stair-equivalents (1 stair = 0.20 m). • Cumulative descent — useful for trail running and post-climb verification. • An altitude profile chart per session you can scroll through later. • Live Activity card on the Lock Screen and Dynamic Island while a session runs. • Apple Watch companion app for wrist-only sessions. • Home Screen widget with today's metres and a 7-day sparkline.

PRIVATE BY DESIGN No account. No cloud. No third-party SDKs. No analytics, advertising, or attribution. Pressure samples are processed on-device and discarded; only a downsampled session summary is stored in SwiftData. There is no network traffic. Deleting the app removes everything.