Speedometer

A GPS speedometer works differently from your dashboard. Instead of counting wheel rotations, it uses satellite signals to calculate how far your device has moved over a period of time, giving your true speed over the ground. In open conditions with a clear view of the sky, GPS speed is typically accurate to within about ±0.5 km/h.

This is why a GPS reading is often a little lower than your dashboard. Regulations such as UNECE Regulation 39 require that a car speedometer must never display less than your true speed, and permit it to over-read by roughly 10%. Manufacturers therefore calibrate dashboards to read slightly high on purpose, so a GPS speedometer showing 68 km/h while your dashboard shows 72 km/h is normal — and the GPS figure is usually the more accurate one.

Make sure you have approved the site's prompt to "Access Location Services". Furthermore, GPS requires a line of sight to orbital satellites. If you are indoors, in a basement, or surrounded by high skyscrapers, your browser may not get a lock and will display 0.0. Move outdoors or place the phone close to a window in a moving car.

HUD stands for Heads-Up Display. When enabled, it flips the dial displays horizontally (mirror-image). If you place your phone flat on your car dashboard at night, the reflection on the windshield will read correctly, allowing you to monitor speed without taking your eyes off the road.

Yes. Speedometer Simple is free to download on the App Store and free to use, supported by ads. Optional in-app purchases (Remove Ads and Premium) are available — prices vary by country and are shown in your local App Store. It requires iOS 15 or later and runs on iPhone and iPad.

Yes. The iOS app uses the phone’s GPS hardware, which needs no internet connection — speed, distance, and trip recording all work with zero signal, as long as the device can see the sky. Only this web version needs internet to load.

Because GPS measures ground speed, one tool covers every activity: driving, where it acts as a second opinion on the dashboard or a temporary replacement if your instrument cluster fails; cycling, as a bike speedometer with no wheel sensor or magnet to install; running and walking, for pace tracking; and sailing and boating, where speed is read in knots. Motorcyclists, skiers and skateboarders use the same readings.

The web speedometer needs no installation and is ideal for a quick check or a one-off speed test. The free Speedometer Simple iOS app adds what a browser cannot do: it runs fully offline on hardware GPS with no internet connection at all, records complete trips with distance, average and top speed, offers a large digital display and a classic analog dial, more than 20 colour themes, and HUD mode that mirrors the readout so it reflects correctly on your windscreen at night.

Continuous GPS use does consume more battery than idle use — that’s true of any navigation app. For long drives, the practical setup is a dashboard mount plus a charging cable, which is how most users run it.

Speed is computed on the device from GPS signals. For the specifics of what data the app does and doesn’t collect, check the privacy policy linked from the App Store listing — the privacy label there is the authoritative source.

A speedometer is an instrument that measures and displays the current speed of a vehicle. Traditional car speedometers count wheel or transmission rotations, while a GPS speedometer calculates true ground speed from satellite positioning — which is why GPS readings are generally more accurate.

The speedometer on this page runs entirely in your browser. Allow location access when prompted and your live speed appears on screen. It works on phones, tablets and laptops with GPS or location services, and you can switch between km/h, mph, m/s and knots at any time. Because GPS needs a view of the sky, readings are most reliable outdoors and in a moving vehicle — indoors, in tunnels or between tall buildings the signal may not lock on and the display will stay at 0.

km/h (kilometres per hour) is standard in most of the world. mph (miles per hour) is used in the United States and United Kingdom. m/s (metres per second) is the SI unit, common in physics and engineering. Knots (nautical miles per hour) are the standard for maritime and aviation use — one knot is about 1.852 km/h.