GPS not accurate? Why it happens and how to fix it

Why is my GPS not accurate?

GPS works by receiving weak signals from satellites. Anything that blocks or reflects those signals makes the position worse. The most common causes are:

• You're indoors, or between tall buildings that block and bounce the signal.
• The phone hasn't had time to get a proper fix yet.
• Precise or high-accuracy location is turned off, so the phone uses Wi-Fi or mobile networks only.
• Battery saver is limiting how often the phone checks its location.
• You're on a laptop or desktop, which usually has no GPS chip at all.
• The compass needs calibrating, so the map points the wrong way even though the position is right.

The GPS test shows your coordinates, the accuracy radius and how long the first fix took, so you can see which of these is the problem.

Typical phone GPS accuracy outdoors with a clear sky

3–10 m

What the GPS test labels GPS-level

≤ 20 m

Labelled rough: the fix came from your IP or a cell area

> 200 m

How to test your GPS accuracy

The test asks your browser for high-accuracy location. No map is loaded and your coordinates aren't sent anywhere.

1. Open the GPS test on your phone and press Start.
2. Allow location access when asked. On iPhone, also allow motion access for the compass.
3. Wait for the first fix. Note the First fix time and the Accuracy value.
4. Go outside with a clear view of the sky and stay still for a minute. Watch the Accuracy value fall as more satellites are found.
5. Walk a short distance and check that Speed and GPS heading appear. These are only reported while you're moving.
6. Hold the phone flat and turn on the spot. The compass should follow you smoothly.

What does the accuracy radius mean?

The Accuracy value is a radius in metres around the reported position. Your real position is likely, not certainly, inside that circle. A smaller number is better.

In a browser, the radius is given at 95% confidence, so about one reading in twenty can fall outside the circle. Android's own location API reports a tighter 68% radius, so a native app can show a smaller circle than the browser for the same fix.

The test labels the result as GPS-level, Wi-Fi / cell-level or rough so you can tell at a glance. Altitude is usually only reported with a real GPS fix, so a missing altitude is another sign you aren't getting one.

Why is my laptop's location so far off?

Most laptops and desktops don't have a GPS chip. The browser estimates the position from nearby Wi-Fi networks or from your IP address instead. A Wi-Fi fix can be within tens of metres in a city, but an IP-based fix can be hundreds of metres to kilometres away, sometimes in a different town.

That's normal and can't be fixed with a setting. If you need an accurate position, use a phone outdoors.

What is time to first fix?

Time to first fix (TTFF) is how long the phone takes to find its position after you ask for it. The GPS test shows it as First fix.

A phone that has been located recently, has mobile data and has a clear view of the sky usually gets a fix in a few seconds. One that hasn't used location for a while, is indoors, or has travelled a long way since its last fix can take much longer, because it has to find satellites from scratch. A slow first fix on its own isn't a fault. Test again outside and see if it's quicker.

Turn on high-accuracy location

Both Android and iOS let you trade accuracy for privacy or battery, and these settings are often the cause of a poor fix. Menu names vary by phone and system version.

• Android: open Settings and find Location. Make sure location is on, and look for Location accuracy (sometimes called Google Location Accuracy or high-accuracy mode) and turn it on. Wi-Fi and Bluetooth scanning settings in the same area also help indoors.
• iPhone: open Settings > Privacy & Security > Location Services. Make sure Location Services is on, then open your browser or app in the list and check Precise Location is on.
• Browser: check the site has location permission. If you blocked it before, allow it again from the icon in the address bar or the browser's site settings.

After changing a setting, press Stop and Start again in the GPS test and compare the accuracy.

Check battery saver

Battery saver and low power modes can reduce how often the phone checks its location, or stop location updates when the screen is off. That makes the position lag behind or jump. Turn battery saver off while you navigate, and check the battery check to see whether you're plugged in and how much charge is left.

Calibrate the compass

If your position is right but the map faces the wrong way, the problem is the compass, not GPS. The compass uses a magnetometer, which is easily thrown off by magnets, metal and electronics.

1. Remove magnetic cases or mounts, and move away from laptops, speakers and metal surfaces.
2. Hold the phone and move it in a slow figure-eight a few times, rotating it as you go.
3. Hold it flat and turn on the spot. In the GPS test the compass should follow you smoothly and point the same way as a known direction.

To check the motion sensors more closely, the smartphone test shows gyroscope and accelerometer readings on all three axes. Readings that stay at zero or jump around while you move the phone point to a sensor problem.

Next, check the rest of your phone

If the GPS is fine outdoors but poor indoors, that's normal. If it's poor everywhere after the steps above, restart the phone and test again before considering a repair.

• Run the smartphone test to check the sensors, vibration and touch.
• Check your charge and charging with the battery check.
• Buying a used phone or laptop? Work through check a used laptop before buying for the same kind of quick checks.