A GPS speed reading is an estimate
ClearSpeed GPS Speedometer shows your device’s estimated speed, not a certified measurement. The ± metres beside GPS status describe location accuracy, not an error bound in MPH or knots. ClearSpeed is $4.99 once in the U.S. App Store, with no subscription or in-app purchases.
Where the number comes from
iOS combines satellite signals (GPS and other GNSS systems) with other sensors to produce location updates, each with an estimated speed and a horizontal accuracy. ClearSpeed reads those updates while it's open, converts the speed to your unit, and displays it.
What affects accuracy
- Sky view. Tall buildings, dense trees, bridges, and tunnels block or reflect signals.
- Placement. A phone deep in a bag, a footwell, or under a metallic windshield tint sees less sky.
- Low speed. At walking pace, small position errors are a big fraction of the movement, so readings wander more.
- Just after launch. The first fix can take a few seconds, longer without cellular data.
- Device. Wi-Fi-only iPads have no GPS receiver and usually cannot report speed on the move.
How ClearSpeed handles weak signal
- A status pill shows Good GPS with the reported accuracy, Weak GPS with a reason, or Searching.
- If reported accuracy is worse than about 30 m (≈100 ft), or a reading is stale, the app shows Weak GPS instead of a speed number.
- Displayed speed is smoothed ("Balanced") so it doesn't flicker, and jumps are limited to what's physically plausible.
- Trip distance ignores implausible position jumps, and trip time pauses while the signal is unusable.
Weak GPS or no speed: what to check
- Check location permission while stationary. Open Settings → Privacy & Security → Location Services → ClearSpeed GPS. Allow access while using the app and turn on Precise Location. Approximate location is not sufficient for this speed display.
- Check the device. iPhone and Wi-Fi + Cellular iPad models have GPS. Wi-Fi-only iPads do not gain a satellite receiver from a phone hotspot.
- Give the device a clear view of the sky. Move out of buildings and away from obstructions when safe. Allow time for a fresh fix; reopening repeatedly does not remove physical signal blockage.
- Keep ClearSpeed in the foreground. It measures while open on screen. It does not keep recording a trip in the background or with the display locked.
- Read the status reason. If GPS remains weak or searching, treat speed and trip totals as unavailable or incomplete rather than assuming the last number is current.
Apple explains location permissions, Precise Location and GPS-capable iPads in its Location Services guide. If the problem continues, use ClearSpeed support with your device and app version.
Does a GPS speedometer work offline?
ClearSpeed can display GPS speed without an internet connection. Mobile data and a usable GPS fix are different things. You still need location permission, GPS-capable hardware and reception. With poor sky visibility, an offline app cannot create a reliable fix. There are no downloaded maps to install because ClearSpeed does not provide maps.
How accurate is it?
There is no single accuracy figure for every iPhone, speed, and environment. Reception, device hardware, movement, and update timing affect the estimate. A GPS reading can lag during acceleration or change at very low speeds. Neither a clear status indicator nor a stable number makes the app a certified instrument. Do not use a phone comparison to calibrate a vehicle instrument.
Try it on your next trip
ClearSpeed GPS is $4.99 once in the U.S. App Store, with no subscription, in-app purchases, or ads. View ClearSpeed GPS on the App Store.