The GPS signal quality shows here after you press Start.
Safety: GPS speed lags by a second or two and is only an estimate. Use your car's speedometer for driving decisions. A passenger should hold the phone. Do not touch the phone while driving.
Private: your location stays on this device. It is not saved and not sent anywhere. Only your unit and limit settings are remembered in this browser.
About the speedometer
This page turns your phone into a GPS speedometer. There is nothing to install. Press Start, allow your location, and your speed appears on a clean dial with big digits.
It works for a car, a bike, a boat, a run or a train ride, as long as the phone can see the sky.
Your location stays on your phone. Nothing is saved or sent.
Features
- Live speed — a dial and big digits, updated each time the GPS gives a new reading
- Three units — km/h, mph or knots, and the page remembers your choice
- Trip numbers — top speed, average moving speed, trip distance and trip time
- Signal check — GPS accuracy and a plain note on how much you can trust the reading
- HUD mode — mirrored digits on a black screen, to reflect in a windshield
- Speed limit warning — set your own number and get a red warning and a beep
- Screen stays on — uses the Wake Lock feature where the browser has it
- Jump filter — ignores sudden GPS jumps, so they do not add to your distance or top speed
How to use it
- Open this page on your phone and go outside, or sit near a car window
- Press Start and choose Allow when the browser asks about your location
- Wait for the signal note to say Good or Strong
- Choose km/h, mph or knots
- Type a speed limit if you want a warning
- Press Stop to pause the trip, or Reset to clear it
If you are in a car, the passenger should do all of this. If you are alone, set it up before you drive and do not touch the phone on the road.
How GPS measures your speed
Your phone listens to satellites and works out how fast its position is changing. Most phones give the speed directly. If your browser does not give it, this page works it out from the distance between two positions and the time between them.
Because of this, GPS speed always comes a little late, often by a second or two. When you brake hard, the number drops after the car has already slowed down. That is why it is an estimate for interest, not for driving decisions.
Signal quality
The accuracy number says how far off the position may be. Smaller is better.
| Accuracy | Signal | What it means |
|---|---|---|
| Up to 10 m | Strong | Good for speed and distance |
| 10 to 25 m | Good | Small errors are normal |
| 25 to 60 m | Weak | Numbers can jump |
| Over 60 m | Very weak | Not counted in the trip |
Roofs, tall buildings, tunnels and thick trees block the signal. Some car windshields with a metal coating do too. If the signal stops for 6 seconds, the page hides the speed instead of showing an old number.
HUD mode on a windshield
HUD means head-up display. It shows the speed on the windshield, so you can read it near your line of sight.
Press Start, then HUD mode. The screen turns black with big mirrored digits. Lay the phone flat on the dashboard, with the top of the picture towards you. The digits then read correctly in the glass. Use Mirror to turn the mirroring off if you want big digits to read directly.
It works best at night. By day, the reflection is hard to see. Make sure the phone cannot slide, and do not put it where it blocks your view or an airbag.
Frequently asked questions
Why is it different from my car's speedometer?
Many car speedometers are made to read a little high, so GPS often shows a few km/h less. Tire size and wear change the car's number too. Follow your car's speedometer and the road signs.
Why does it say desktop computers have no GPS?
Almost all desktop computers and many laptops have no GPS chip. The browser can only guess the place from Wi-Fi, which is too rough to measure speed. Open the page on a phone.
Why does it ask for my location?
GPS speed comes from your location, so the browser must ask you first. It asks only after you press Start. If you said no by mistake, allow location for this site in your browser settings and press Start again.
Does it work when the screen is off or in another app?
Usually not. Phones can pause the GPS for a web page that is not on screen. Keep the page open. The page tries to keep the screen on. If your browser cannot do that, it tells you, and you can set a longer screen timeout.
Why does the distance look too short?
The page ignores small moves that could be GPS noise, and it draws straight lines across signal gaps. Long stretches without a signal and many sharp turns can make the number a little low.
Good to know
- GPS speed is an estimate. Do not use it for driving decisions or to argue about a speeding ticket
- The speed limit warning uses your own number. The page does not know the real limit of the road
- Top speed needs the same high reading more than once, so one bad reading cannot set it
- A reload clears the trip, because nothing is saved
Related tools
- Online Compass — see which way your phone points
- Bubble Level — another tool that uses your phone's sensors
- KMH to MPH — convert a speed from km/h to mph
- Fuel Cost Calculator — work out what a trip costs
- Tire Size Calculator — see how new tires change your speedometer
