Speedometer, in your browser.
Press Start and allow location. Your phone's GPS gives the speed. Use it on a phone, outside or by a window.
Free · runs in your browser · nothing is sentPress Start and allow location
- Max
- –
- Distance
- –
- Time
- 0:00
Your location stays in this browser: nothing is sent or saved. The page keeps your screen on. If you lock the phone or switch apps, the browser stops reading GPS. The Speedometer app keeps recording a trip with the screen off.
How to use it
- Open this page on a phone. Press Start and allow location.
- Wait for the first GPS fix. Outside it takes a few seconds; indoors it may never come.
- Read the speed. Max, Distance and Time add up until you press Reset.
Set it up before you drive, and let a passenger read it. In many places it is illegal to touch a phone while driving.
How a phone knows its speed
A GPS chip does not only find where you are. It also measures how the satellite signals shift in frequency as you move toward or away from each satellite (the Doppler effect). From that it works out your speed directly, many times a second, without comparing two positions. That is why GPS speed is steady at a constant speed, but needs a view of the sky: tunnels, garages and tall buildings block it.
| Where | What to expect |
|---|---|
| Car, bike or walk, open sky | Steady, usually within 1–2 km/h |
| Train or bus, by a window | Good, with gaps in cuttings and stations |
| Plane, by a window | Often works at cruise; some browsers stop in flight mode |
| Indoors, tunnel, garage | No signal: the page says so and shows a dash |
| Laptop or Wi-Fi-only tablet | No GPS: a position from Wi-Fi, no real speed |
Units
1 km/h = 0.621 mph = 0.540 knots. 100 km/h is 62 mph; 60 mph is 97 km/h. Knots are nautical miles per hour, used at sea and in the air.
Why the app, if the page works?
A browser reads GPS only while the tab is open and the screen is on. Lock the phone or open a map app and the page stops, so the trip misses part of the road. A browser also does not say how sure its speed is, and some browsers give no speed at all.
The Speedometer app keeps recording a trip with the screen off or in another app, with the speed in the notification. It shows the phone's own speed accuracy on every reading (for example “± 1 km/h · 14 satellites”), a large dial you can read at a glance in a car mount, a speed alert that fills the dial with colour, and a mirrored head-up display for the windshield. No ads, nothing ever covers the speed.
Questions
Is this online speedometer free?
Yes. No account, no ads, nothing to install. It remembers only your unit, in your own browser.
How accurate is it?
The speed comes from your phone's GPS. Most phones measure speed from the Doppler shift of the satellite signals, which is usually within 1 to 2 km/h when the phone can see the sky. A browser does not report that accuracy, so the page shows the position accuracy instead. When the browser gives no speed, the page works it out from two positions and says so; that is less exact, mostly at low speed.
Why does it show 0 or a dash on my laptop?
Laptops and most tablets have no GPS chip. They find their place from Wi-Fi, which gives a position but no speed. Use a phone, outside or in a car or train with a window.
Does it work with the screen off?
No. A browser stops reading the location when the screen locks or when you switch to another app. The page keeps your screen on while it runs. For a trip with the screen off, use the Speedometer app.
Is my location sent anywhere?
No. The page reads your location in your browser to show the speed and adds up the distance there. Nothing is saved or sent, and the page stops reading the location when you press Stop.
Why does my car show a higher speed?
Most car speedometers read a little high on purpose: many countries' rules allow a car to show more than the true speed, never less. A difference of a few percent is normal. GPS speed is usually the closer one on a straight, level road.