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ToolsWiFi speed test

Is it WiFi or the line?

WiFi
speed test

A wifi speed test usually reads lower than the line feeding it, because walls, distance and other devices cut the speed. A result much lower in one room than by the router points at the wifi.

Ready to measure

Is it WiFi or your line?

~20 seconds, then a 1-minute follow-up that tells WiFi from the line

Runs in your browser · no data leaves your device

If your internet feels slow, the cause is almost always your WiFi, not your broadband line. We run a normal speed test, then walk you through a one-minute check that tells you which one is actually at fault.

Run this from the room where your WiFi feels worst, that's the test that matters.

How we measure: The test runs in your browser against the nearest UK edge. How we diagnose: we join your result to the line + deal data we hold for your address.

Read the full methodology →

Questions

Wifi speed questions

Is the problem my wifi or my broadband?

Run this test in the room where it feels slow, then plug a laptop into the router with a cable and test again. If the wired result matches your package and the wifi one is much lower, it's the wifi: distance, walls, interference or an old router.

What's a good wifi speed?

Close to the router, wifi should get near your wired speed. It drops with distance and walls, and older routers can't reach the top speeds of fast full fibre lines.

How do I fix slow wifi?

Restart the router, then move it somewhere central and in the open, away from metal and thick walls. If far rooms are still poor, a mesh system or an extender spreads the signal. A newer router helps most on fast lines.

Our router guide →

Wi-Fi speed test

Wi-Fi speed test

Updated 25 October 2026

A wifi speed test measures something your bill never mentions: the speed that actually reaches the spot you are sitting in, after the walls, the distance and your devices have taken their cut. The test above runs at your device, not at the line, so the number it gives is usually lower than the one you pay for. The gap between the two is the most useful thing on this page. Here is how to read it.

Judge it against the room, not the headline on the box. A single 4K stream wants about 15 Mbps on Netflix, an HD stream about 5 Mbps and a video call about 3 to 4 Mbps, so a wifi reading of 50 to 100 Mbps where you actually sit is plenty for most homes, even if the line into the house is far faster. What matters is that the number clears what that spot is used for. A reading that comfortably covers your streaming and calls is a pass, however far it sits below the speed on your contract.

Wifi is radio, and radio fades. Every wall, floor and closed door between you and the router takes a slice, and distance does the rest, so a test next to the router and a test two rooms away can differ a lot on the same line in the same minute. The band matters too: the 5GHz band is fast but short-range, the 2.4GHz band reaches further but carries less, and your phone hops between them without telling you. The device itself can cap things, since an older phone or laptop simply cannot pull a modern full-fibre speed out of the air. None of that is a fault, which is the whole point: a wifi number on its own cannot tell you whether the weak link is your wifi or the line behind it.

One follow-up settles it. Plug a laptop straight into the router with an ethernet cable and run the test again. If the wired result is fast and the wifi one is not, the line is fine and your wifi is the bottleneck, which is good news because wifi is the cheap thing to fix: move the router out of the cupboard and up off the floor, get on the 5GHz band when you are close, add a mesh point for the rooms the signal cannot reach and wire in anything that stays put. Our full wifi guide runs through them in order.

If the wired test is also slow, the line is the limit and no amount of router-shuffling will lift it. Good wifi can only share out what the line brings in, and full fibre brings in the most. The test above shows the lines that actually deliver at your address, so your wifi finally has something worth spreading around.