Wi-Fi speed test: how to do it and read the result

The order you test in matters more than the tool you use. Run it wrong and you measure your wifi when you meant to measure your line, or the other way round, and the number sends you off fixing the wrong thing.

Start wired if you can. Plug a laptop straight into the router with an ethernet cable and run the test there first. That result is your line speed, the honest figure with the wifi taken out of it, and it is the one to compare against the speed you are paying for. Then unplug and run the test again from where you actually use the connection, the sofa or the spare-room desk. The difference between the two is your wifi tax, and knowing it is the whole game. Our wi-fi speed test runs in the browser, so close the other tabs and pause any big downloads before you press go, and test one device at a time so nothing else on the line muddies the figure.

A wifi result lower than your headline speed is not a fault. It is physics, and a few things drive it.

Distance and walls are the big ones. Wifi is radio, and radio fades the further it travels and weakens every time it passes through a wall, a floor or a mirror. A test next to the router and a test two rooms away can differ by more than half, on the same connection, in the same minute. The band matters too: most routers broadcast on both 2.4GHz, which reaches further but carries less, and 5GHz, which is much faster but does not travel as well, and your device picks between them without telling you. Then there is the kit at your end. An old phone or a laptop with a dated wifi card cannot physically receive a modern full-fibre speed over the air, so the test caps out well below the line regardless of how good the broadband is.

None of that means your broadband is broken. It means a wifi number on its own cannot tell you whether the line or the wifi is the weak link. For that you need the wired baseline, which is why the order above matters.

Read the wifi result against two things: the speed you pay for and what you actually do online.

If your wired test lands near your plan and your wifi test in the room you use comes in comfortably above what that room needs, you are fine, even if the wifi number is well under the headline. The per-activity sums live in what speed you actually need, but as a rough floor a single 4K stream wants about 25 Mbps and a video call only a few, so a wifi result of 50 to 100 Mbps at the sofa is plenty for most homes whatever the box says. Do not stop at the download figure, though. The upload result matters as much for video calls and cloud backups, and ping, the responsiveness number, is what decides whether calls and games feel sharp. A big download with a poor upload or a high ping is still a poor connection for the things that need them.

This is the question the two tests answer between them. If the wired test is slow, near or below the wifi figure, the problem is the line or the deal, and no amount of router fiddling will fix it. If the wired test is healthy but the wifi test collapses as you move through the house, the line is fine and the problem is coverage.

Most slow broadband is the second kind, a wifi problem wearing a broadband problem's clothes. If you suspect the box, work out whether your router is the problem first, and the wider list of fixes lives in how to speed up your broadband. Work through those before you so much as look at a new contract, because an upgrade buys you nothing if the speed was dying in the hallway.

If the wifi is the weak link, the fixes are cheap and they go in order. Move the router first: out of the cupboard, off the floor, central and high, away from the microwave and the fish tank. Get on the 5GHz band when you are near the router, since it is far faster than the 2.4GHz one most kit defaults to. For a spot the signal cannot reach, a mesh system beats a faster broadband package every time, because it fixes coverage rather than throwing speed at a wall the speed cannot cross. And for anything that stays put, a games console or a desk, wire it in and take the wifi out of the equation entirely.

If the wired test is the one that disappoints, the fix is the line, not the kit. Here are the live full-fibre deals at your address, the connection that actually delivers the speed your wifi then shares out, from the cheapest going to the fastest.