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Why faster broadband won't make one device faster (and why speed tests mislead)

By Chris Davies · Updated

Quick answerUpgrading from 80Mbps to 500Mbps or 900Mbps doesn't make a single phone or laptop 10 times faster. Each device has its own ceiling, set by its WiFi chip, the walls and the distance to your router. What a faster package does is give the whole household more room, so everyone can stream, call, game and download at once without slowing each other down. That's why one speed test on one device isn't a fair verdict on your package.
1 devicehas its own speed ceiling
Whole homeis what a faster package speeds up
1 testmeasures your setup, not just your line

Think motorway lanes, not speed limits

Your broadband package is like a motorway. Upgrading from 80Mbps to 500Mbps doesn't raise the speed limit for each car: it adds more lanes. One car on an empty road goes no faster with six lanes than with two. But at rush hour, when everyone's on the road, the extra lanes are the difference between flowing traffic and a jam.

In your home the "cars" are TVs, laptops, phones, consoles, tablets, doorbells and smart speakers. The average UK home now has well over a dozen connected devices, and in the evening many of them are busy at the same time.

The key ideaA faster package is about capacity: how much the whole household can do at once. It isn't a promise that one device will run at the full package speed.

What 8pm actually looks like

Stacked bars: a busy family home needs about 226Mbps at 8pm, which overflows an 80Mbps package but fits easily in 500Mbps
Two 4K TVs, a video call, a game download and everyone's phones add up quickly. On 80Mbps they fight over the space; on 500Mbps everything fits.

None of those devices needs 500Mbps by itself. The 4K TV only wants about 25Mbps. But add them together and the household needs far more than any single device does. That combined demand is what you're really paying for when you upgrade.

Every device has its own ceiling

Bar chart of typical single-device speeds on a 900Mbps line: older phone 70, smart TV 95, laptop upstairs 200, new phone near router 600, laptop on cable 900
On the same 900Mbps line, different devices reach very different speeds. Only a modern device on a cable gets close to the full package.
Good newsYour devices don't need the full speed. A 4K stream is happy at 25Mbps. What makes them feel slow is other devices competing for the line, and that's exactly what a bigger package fixes.

Why a speed test isn't a fair check on your package

A speed test result surrounded by six things that affect it: WiFi signal, your device, others online, the test server, time of day and apps or VPNs
A speed test on your phone measures your WiFi, your device, everyone else using the line and the test server, not just your broadband connection.

When you run a speed test on your phone from the sofa, you're measuring the whole chain: your phone's WiFi chip, the walls between you and the router, whatever else the household is doing, and a test server that might be busy or far away. If your phone reports 187Mbps on a 900Mbps package, it usually means your phone or your WiFi is the limit, not the line.

That's why "I pay for 900Mbps but my speed test says 200" rarely means you're being short-changed. Your package is still delivering 900Mbps of capacity to the house; one device just can't use all of it.

Fair to providers, fair to youProviders following Ofcom's broadband speeds code give you a minimum guaranteed speed when you sign up, measured to the router, not to a device on WiFi. That's the number to hold them to.

How to test your broadband properly

  1. Use a cable. Plug a modern laptop into the router with an Ethernet cable (gigabit or better).
  2. Pause everything else. Stop streams, downloads, game updates and cloud backups, or test when the house is quiet.
  3. Close apps and switch off your VPN.
  4. Test a few times at different times of day, and use your provider's own speed checker as well as a general one.
  5. Restart the router if results are consistently low, then test again.
  6. Compare with your minimum guaranteed speed, not the headline package speed.

So what should you pay for?

Choose for the household, not the deviceCount how many people and devices are busy at your busiest time. One or two people who mostly browse and stream: 30–80Mbps. A family with 4K TVs, gaming and home working: 150–500Mbps. Large or very heavy households: 900Mbps and up. Then fix coverage separately with good router placement or mesh WiFi.

Cooper asks how many devices you have and how you use them, then recommends a package that fits your whole home, not just your fastest gadget. See also what broadband speed do I need? and 12 ways to speed up your WiFi.

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Frequently asked questions

Will faster broadband make my phone faster?

Only up to a point. Your phone has its own ceiling set by its WiFi chip and your signal. A faster package mainly means your phone doesn't slow down when everyone else is online too.

Why does my speed test show less than I pay for?

Usually because you are testing over WiFi, on a device that can't reach the full speed, or while others are using the line. Test on a cable with nothing else running to see your real line speed.

Are speed tests accurate?

They accurately measure what one device gets at that moment, which depends on your WiFi, device, other users and the test server. They aren't a reliable measure of your whole package unless you test wired with nothing else running.

Is it worth upgrading if one device is slow?

Not if that device is the bottleneck. Fix WiFi coverage or the device first. Upgrade your package when several people or devices compete for the line at busy times.

What speed am I guaranteed?

Providers that follow Ofcom's broadband speeds code must tell you a minimum guaranteed speed at sign-up. If your speed falls below it and they can't fix it, you can usually leave without penalty.

Related guides

What broadband speed do I need? (UK guide)Work out how much broadband speed your household really needs for streaming, gaming, video calls and working from home, with simple rules of thumb.How to speed up your WiFi: 12 fixes that workSlow WiFi? Practical fixes, from router placement and channels to mesh systems and wired connections, before you pay for faster broadband.Do I need mesh WiFi?Whether mesh will fix dead spots, mesh vs boosters, and how many discs you need.