Broadband speed test: Which? expert advice

Don't just go by your provider's promise on broadband speed. Use the Which? free speed test to investigate.

Here we explain how to use the speed checker. If your broadband isn't as fast as it should be, read our advice on how to speed up your connection.

How to use our broadband speed checker

For the most accurate results, use an ethernet cable to connect your computer to your router before running the test. If you need to test wirelessly, get as close to your router as possible.

You should also make sure nothing else is using your internet connection or running on your computer when you do the test. 

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What do the broadband speed test results show?

The tool measures the response time – also known as latency – of your broadband connection, as well as your download and upload speeds.

• Response time is measured in milliseconds (ms) and shows how quickly you get a response after you've sent out a request. More responsive connections are those with a low number of ms (meaning they take less time to respond). This particularly sought after for applications where timing is everything, such as interactive video games.
• The download speed shows the rate at which data is transferred from the internet to your device – how quick it is to access a newspaper article online or stream music, for example. It's measured in megabits per second (Mbps) – the higher, the faster.
• The upload speed shows the rate that data is transferred from your device to the internet – how quick it is to upload a photo or document to an email, for example. As with download speed, it's measured in megabits per second.

Download speeds are usually of more interest, as most tasks require you to download information, for example searching online for information. Download speeds are also usually what are advertised to you by broadband providers. However, if you use your broadband connection for video calls or online gaming, keep an eye on the upload rate too, as it's essential for both. 

To build an accurate picture, run several tests during a single week, in peak-use time (between 8pm and 10pm) and during off-peak times.

The results also only show the speeds you're getting on the device you're using for the test. The speed your provider is delivering to your home may be higher, especially if you're performing the test wirelessly at some distance from your router.

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What you can do if your broadband speeds are slow

If your speeds are significantly less than you expected, check our advice on how to speed up slow broadband.

If you've done everything you can to speed up your connection and you're still getting a lower speed than you were promised, your broadband provider may be in breach of contract. 

Call your internet service provider (ISP) as a first step to see what it can do. Start by providing evidence of your internet speeds (it's a good idea to keep a diary of interruptions and to regularly use the speed checker tool to build up a true picture of your service). 

If your broadband contract started after March 2019 and you're with one of the providers that's signed Ofcom’s voluntary code of practice (BT, EE, Plusnet, TalkTalk, Utility Warehouse, Virgin Media and Zen Internet), your provider must give you a minimum guaranteed speed when you take out a new contract. 

If your speed drops below this, your provider must improve it within a month. If it can't, it must allow you to exit your contract penalty-free. If you're not happy with your ISP's response, follow our guide on how to complain about your broadband speed.

Shop around for the best broadband deal

It's always worth checking to see what broadband deals are on offer from other providers, especially if you're out of contract and could stand to make significant savings. Enter your postcode below to see deals in your area, or check our pick of the best broadband deals.

Compare broadband deals

Use Which? to search for faster, more reliable broadband services.

Members who switch before 20 April will get an Amazon.co.uk gift card up to £100.

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Offer ends 20 April, T&Cs apply

Which? Member exclusive up to £100 gift card

For a limited time, Which? members will receive a £25 gift card if they switch to any provider using our comparison service. Choose Zen Internet, a Which? Recommended Provider, and get a £100 Amazon gift card.

This offer ends on April 20, and terms and conditions apply – head to our broadband comparison service to find out more.

Already a member? Log in here, or Join Which? to unlock our exclusive offer.

Our pick: NOW Full Fibre 100

This is a particularly attractive fibre broadband deal given the 100Mbps average speeds. Now Broadband implements ad-hoc price increases: in July 2023 products increased by £3.50 (social tariffs were excluded from the price rise). Read our NOW Broadband review to see how it fares in our survey. 

Other broadband-only deals to consider

Alternatively check the broadband-only deals below for more packages we think represent good value for money.

Which are the best broadband providers?

If you're unhappy with your current broadband provider, consider one of our top-rated providers instead. We can't guarantee they will give you the fastest speeds, but they convincingly beat the other major providers in our unique Which? broadband satisfaction survey. 

Top-rated providers: broadband

Zen Internet is currently our only Which? Recommended Provider thanks to its strong customer score and commitment to both Ofcom's voluntary schemes and fixed prices throughout its contracts.

Join Which? to reveal the full results of our broadband provider customer satisfaction survey and in-depth provider reviews, or if you're a member simply log in to unlock the detail in the table below:

Read our guide to the best and worst broadband providers to see how all the big providers were rated.