GPS test
Your phone always knows roughly where it is — from Wi-Fi, from cell towers, from anything nearby. Whether the satellite receiver is actually working is a different question, and it has two tells: an uncertainty radius that drops under about fifteen metres, and an altitude. This watches for both, times how long the fix takes, and says which kind of position you are getting.
Go outside, or at least to a window. Satellites do not reach far indoors, and a fix that fails in a basement says nothing about the phone.
- Best radius—
- Time to satellite fix—
- Altitude—
- What it looks like—
- Fixes received0
Coordinates are rounded to about a hundred metres and never leave this page. Nothing is sent anywhere.
- Verdict—
Did it reach a satellite fix?
Running it
Go outside, or to a window at the very least, then start. The phone will answer at once with a wide radius — hundreds of metres, sometimes kilometres — and the number will fall as satellites lock. Watch for the collapse: when the radius drops under fifteen metres and an altitude appears, that is a satellite fix, and the time it took is shown.
The test stops itself once the fix is tight and steady, or after ninety seconds if it never gets there. You can stop it earlier.
Reading the result
Satellite fix. The radius is under fifteen metres, or the phone is reporting an altitude, or both. The receiver works. Anything still wrong with navigation is somewhere else — and the usual somewhere else is the compass rather than the receiver, because the two faults look identical on a map. A receiver decides where the arrow sits; the magnetometer decides which way it points, and a phone that knows its position perfectly while facing the wrong way has a calibration problem the sensor test shows in seconds.
Wi-Fi positioning. The radius settled somewhere between fifteen and a hundred metres and no altitude ever appeared. Indoors this is exactly what a healthy phone does, and it means nothing. Outdoors, under open sky, after a couple of minutes, it means the receiver is not contributing.
Cell or network only. Hundreds of metres or more, no altitude. Either there is no Wi-Fi around to help and no sky to see, or location is on but the receiver is off — some battery-saving modes do this — or the receiver has failed.
Time to fix is the number to compare between phones or over time. A receiver that takes a minute where another phone in the same spot takes ten seconds is the weaker of the two, and one that used to be quick and no longer is, is on its way out.
Why a receiver fails
The antenna. It is not a rod but a flat strip or a patch inside the case, often near the top edge, and it is connected by a thin flexible cable that is easily disturbed. Drops do it. Water does it — corrosion on the connector is a classic. Screen replacements do it when the technician forgets to reconnect the strip, which is worth remembering when a phone has plainly been repaired before.
And then there are cases. A case with a metal plate for a magnetic mount, a metallic finish, or a battery pack built in will attenuate the signal noticeably. If the fix is slow or weak, take the case off and run it again before concluding anything about the phone.
Android
- Settings → Location has to be on, and under Location services the Google Location Accuracy option is what allows Wi-Fi and cell to help — with it off, the phone relies on satellites alone, which is a useful way to isolate the receiver.
- Battery saver modes on several makers restrict location in the background and sometimes in the foreground too. Test with battery saver off.
- GPS-only mode or Device only where the maker still offers it is the strictest test: no Wi-Fi assistance at all. A fix in that mode is a fix from satellites and nothing else.
iPhone
- Settings → Privacy & Security → Location Services has to be on for the phone and for Safari. Safari also has to be granted permission for this site — a Precise Location toggle appears in that prompt, and with it off the phone deliberately reports a coarse position that will never reach a satellite fix here.
- Low Power Mode does not switch location off but does slow background refresh. It is worth turning off while testing.
- Apple blends sources aggressively and rarely reports altitude from anything but satellites, which makes the altitude tell reliable on an iPhone.
When buying a used phone
Run this outside before money changes hands — it is the one test in the checklist that cannot be done in a shop or a hallway. A phone that will not fix under open sky has either a failed antenna or a bad repair behind it, and both cost real money to put right. It also fails from the same drops and water that damage everything else, so a fault here is a reason to look harder at the rest.
Common questions
How does this tell GPS from Wi-Fi positioning?
It cannot ask. The browser receives one blended position from the operating system, which combines satellites, Wi-Fi and cell towers and does not say what it used. But the sources leave different fingerprints. Wi-Fi positioning settles at a radius of twenty to sixty metres and never gets much better, because that is how precisely a database of access points can place you. Cell towers give hundreds of metres. Only satellites bring the radius under fifteen. And a satellite fix carries an altitude, while a Wi-Fi fix does not, because a database of routers knows where they are but not how high. Either one is suggestive. Both together are the answer.
Why does the radius start huge and then shrink?
Because the phone answers immediately with whatever it has — usually a Wi-Fi or cell estimate with a wide radius — while the receiver is still listening for satellites. A cold receiver needs to hear several of them and download their orbits, which takes anything from a few seconds to a minute or so with a clear view of the sky. The moment enough satellites are locked, the radius collapses. That collapse is the thing to watch for, and the time it takes is worth knowing: a receiver that needs three minutes for a fix that used to take ten seconds is one that is starting to fail.
It says Wi-Fi positioning but my GPS works fine in maps.
Almost certainly you are indoors. Satellite signals are weak — roughly the power of a light bulb, broadcast from twenty thousand kilometres — and a roof, a few floors of concrete, or even a car park stops them. Go to a window at the very least, and preferably outside with sky above you. If the radius still does not drop after a couple of minutes there, then it is the phone.
Does this work on a laptop?
It runs, and it will report Wi-Fi positioning, because almost no laptop has a satellite receiver. That is the correct answer rather than a failure. The test is for a phone, or for the occasional tablet with a receiver in it.
Where does my location go?
Nowhere. The position is read inside this page and used to draw the radius and the readout, and that is all. The coordinates shown are rounded to three decimal places, which is about a hundred metres — enough to see that the phone found the right neighbourhood, not enough to identify a building from a screenshot. Nothing is sent to this site or to anyone.
What is a normal time to fix?
On a modern phone outdoors, under thirty seconds from cold and a few seconds when it has been used recently, because the orbit data is still fresh. A minute is acceptable in a city with tall buildings around you. Beyond three minutes with a clear sky, it is not going to arrive.