How fast am I going?

A speedometer is an instrument that measures and displays the instantaneous speed of a vehicle or person — how fast you are moving right now, as opposed to how far you have gone. Traditional car speedometers count wheel rotations through a cable or a sensor and convert that into km/h or mph. A GPS speedometer like this one reaches the same answer from satellite signals instead, so it needs no mechanical connection to anything and works on foot, on a bike, on a boat or in any vehicle.

Mainly to stay within the speed limit and to drive or ride at a safe, steady pace. Beyond that it is used to check the accuracy of another speedometer, to pace a training run or ride, to measure acceleration, to hold a legal speed on the water, and to log a journey — distance, duration and average speed all fall out of a continuous speed reading. This page covers all of those: live speed, trip statistics, a 0–60 timer and exportable trips.

A GPS speedometer measures how fast you are travelling using satellite navigation signals instead of a mechanical link to your wheels. Because it reads your motion directly rather than counting wheel rotations, it is unaffected by tyre size, tyre pressure or wear — which is why a GPS speedometer is often used as the reference to check a car speedometer against.

Under a clear sky a modern phone reads speed to within roughly 1 km/h. GPS speed is usually derived from the Doppler shift of the satellite signals rather than from position changes, which makes it more accurate than most people expect — often more accurate than the speedometer in your car. Accuracy degrades in tunnels, dense cities and deep valleys, so this page shows you the accuracy radius rather than hiding it, and discards fixes worse than 30 m. More on GPS speed accuracy.

Yes, and it is expected. Your dashboard will normally read a little higher than the GPS figure — typically 2–5%, with the gap widening as you go faster. The car reads wheel rotations and multiplies by an assumed tyre circumference, then adds a deliberate safety margin; GPS measures your actual movement over the ground and adds no margin at all. At an indicated 100 km/h you are often truly doing 95–98. Full explanation here.

Not exactly, and by design. Regulations in the EU, the UK, Australia and most other markets forbid a car speedometer from ever under-reading, so manufacturers build in a margin and the dial errs high. Worn tyres, a different tyre profile or a non-standard wheel size shift the reading further. That is why a car speedometer is a safe instrument but not a precise one — to see your true speed, hold a steady pace on a level road and read the GPS figure here.

Usually one of three things: your first satellite fix has not arrived yet (this can take up to a minute from cold), you are indoors or in a covered area with no clear view of the sky, or you are moving slower than walking pace, which we treat as stopped so that GPS jitter does not accumulate phantom distance. Watch the accuracy figure in the status bar — if it says ±30 m or worse, readings are being filtered out on purpose. Check too that you granted the location permission when the browser asked. Fix a blocked location permission on iPhone or Android.

HUD stands for heads-up display. In HUD mode the speed is shown very large on a black background, and the Mirror button flips it horizontally, so a phone resting face-up on the dashboard projects a reflection into the windshield that reads the right way round. You see your speed without looking down. Set it up before you move, never while driving.

Yes. On a bike it replaces the magnet, fork sensor and wheel-circumference calibration of a traditional bicycle speedometer — mount your phone and you have live speed, distance, moving time and full trip statistics. On the water, knots are one of the four units, and the open sky gives the best accuracy you will get anywhere. For running, skiing, skating or any other sport the trip statistics work identically, and every session exports as GPX for Strava, Garmin Connect or Komoot. Cycling guide · knots for boating.

Continuous high-accuracy GPS is inherently power-hungry on any device, and keeping the screen awake for a visible speedometer adds to that — expect noticeably faster drain than idle use. For long drives or rides, plug in. If you only need the numbers, staying in digital mode does less work per second and helps a little.

Yes. Every feature is free, with no download, no sign-up and nothing gated behind an app. Advertising pays for the site, so there is no paid tier and nothing is held back for one.

The speedometer itself does. GPS is a one-way satellite signal and needs no data connection, so once the page is loaded your speed, distance and trip stats keep working offline. Nothing needs the network at all — install the page to your home screen and it will keep working in areas with no signal.

Get onto a straight, level road with a clear view of the sky, hold a steady indicated speed, and compare your dashboard against the live GPS reading here. Take the comparison at two or three speeds — 50, 80 and 110 km/h, say — because the error is usually proportional rather than fixed. Have a passenger read the screen; never do it yourself while driving.

No. This is a static page with no backend. Your browser hands the coordinates to the JavaScript running on your own device, the numbers are calculated there, and saved trips are written to your browser’s local database. There is no account to create and nothing to upload.

Press Start on the speedometer above, allow location when your browser asks, and your current speed appears within a few seconds, in km/h, mph, m/s or knots. It reads directly from the GPS receiver in your device, so it works in a car, on a bike, on a boat, on a train or on foot, and it needs no app. If the dial stays at zero, give the receiver a clear view of the sky and wait for the accuracy figure to settle.

Yes, without an app. Open this page in Safari, press Start and allow location, and the iPhone’s own GPS shows your speed here in mph or km/h. It keeps working when you are not following a route, which is exactly when map apps show no speed at all. If Safari never asks for your location, here is how to allow it.

Google Maps shows a speedometer only while it is navigating a route, and only after you turn it on: profile picture, Settings, Navigation, then Speedometer under “Driving options” (Google’s instructions). Without a route it shows no speed, and Google itself says to trust your vehicle’s speedometer over it. This page shows your speed the moment you press Start, with or without a destination.

No. The page has no map data and never learns where you are, so it cannot look up the legal limit on the road you are on. What it can do is hold the limit you set: enter one and the dial marks it, converts it when you change units, and warns you the moment you go over. The speed converter has a reference table of the limits you meet most often.