How to Use Your iPhone as a GPS Speedometer

TL;DR

SpeedTrace turns your iPhone into a large, high-contrast GPS speedometer readable at a glance, showing live altitude, compass heading, and session max and average speed — with honest GPS status that never fakes a confident reading on a weak signal.

Steps

Open SpeedTrace and allow location access.
Read your speed in the large, high-contrast display.
Glance at altitude, compass heading, and session max/average.
Note the GPS status — it tells you when the signal is weak.

Why it works this way

A phone speedometer is only useful if you trust it and can read it at a glance. SpeedTrace makes the number big and high-contrast, surrounds it with the context that matters (altitude, heading, your session’s max and average), and — crucially — is honest about GPS: when the signal is weak, it says so rather than showing a confident but wrong number.

Tips & edge cases

Honest GPS status means a shaky reading is flagged, not hidden.
Mount the phone if you’re driving; glance, don’t stare.
Switch units (km/h, mph, knots, m/s) to match your activity.

FAQ

How accurate is the speed? It’s GPS-based, and SpeedTrace is honest about signal — it won’t show a confident reading when the GPS signal is weak.

What else does it show? A large speed readout plus live altitude, compass heading, and your session’s max and average speed.

Do I need a car mount? The readout is high-contrast and glanceable, but always keep your eyes on the road — mount it if you’re driving.