For iPhone and Apple Watch
Your Zone 2 ceiling, measured — not guessed.
Age formulas put your aerobic threshold somewhere in a 15-beat band. DriftTest finds your own number with a test you go out and do: hold one steady pace for 40–60 minutes and read how far your heart rate drifts.
How it works
- Get a starting heart rate. A first target from your age and resting heart rate — then your own measured number from every test after.
- Run the test. Warm up, lock one speed on the treadmill or hold one pace on a flat route, and don't touch it for 40–60 minutes. Record it with Apple Watch or your Garmin, Polar or COROS.
- Read the drift. Pick the run, choose the steady block on the chart, tap Analyze. First half against second half: under 3.5 % and you were below your ceiling, 3.5–5 % and you were on it, more and you were over.
- Get your zones. Once a test lands in band, DriftTest gives you your Zone 2 ceiling and the heart-rate zones that follow from it.
A prescribed test
Not a guess pulled from your workout history. You know exactly what was measured because you selected it on the chart.
Treadmill or road
Indoors the belt holds the pace for you. Outdoors DriftTest checks pace against heart rate, so a slowing pace can't hide the drift.
Any watch
Apple Watch workouts straight from Health, or a .fit file exported from a Garmin, Polar or COROS.
Private by design
No account, no server, no analytics. Your health data is read on your iPhone and never leaves it.
Free to download. One-time purchase to unlock the result — no subscription.