Broadband Speeds Explained

Everything you need to know about broadband speeds and what the terms mean.

It can be difficult to know exactly what speed you're going to get when you sign up for a new broadband service. This guide aims to explain the factors affecting broadband speed, help you understand what the advertised speeds mean and give you the information you need to choose a broadband service with confidence.

How broadband speeds work

Most fixed line broadband services enter your home using your telephone line. Different broadband technologies have different maximum connection speeds, such as 24Mb or 80Mb. However, the actual speed you'll get is affected by how much copper cabling your connection uses - something that even applies to most fibre services.

The use of copper cables explains why there's so much variation in the broadband speeds available, and why you might get a much slower speed than someone living in the same postcode. Simply put, copper cables are not very efficient. They're slow, and the signal they carry degrades the further it has to travel. This means that your broadband speed will be directly affected by how much copper cable is used in your connection. This can be true even if you have a fibre connection. Fibre optic cables are much faster and much more efficient, but most fibre deals still use a small amount of copper along the way.

The majority of UK broadband services are split into two types:

  • Standard ADSL broadband: The broadband signal is carried between your nearest telephone exchange and your home entirely over copper cables. The further away you are from that exchange, the slower your connection will be. This is one reason why rural areas can be stuck with painfully slow broadband.
  • Fibre to the cabinet broadband: Most fibre products in the UK are classed as 'fibre to the cabinet'. Here, fast fibre optic cables are used between the exchange and your nearest street cabinet, but copper cables are used to complete the connection from the cabinet to your home. Your distance from that cabinet will affect your speeds - people living at the opposite ends of the same street could get vastly different speeds as a result.

The main exception to this is Virgin Media. They use Virgin's own coaxial cables to complete the connection from the cabinet to your home. These cables are much faster than the copper phone lines, and enable Virgin to offer packages with speeds up to 300Mb.

There are also some ultrafast and hyperfast broadband services which can deliver even faster performance. A different type of fibre called 'fibre to the home' has the fibre connection running right up to your property, and can provide average speeds up to 900Mb. However, these have a more complicated installation and so mostly only target new build estates and apartment blocks.

The Openreach network, upon which most broadband services run, is also being upgraded to the new technology. This will offer two speed tiers of 160Mb and 330Mb. It's expected to be available to 5.7 million homes by the end of 2020.

Peak time slowdowns

As well as permanent speed limits from copper line length, all broadband services tend to experience some temporary slowdown in the speeds that customers can achieve during peak times.

Due to the nature of typical working and sleeping hours, there are certain times of the day that are more likely to be busy, and others that are likely to be relatively quiet. Even if the provider has invested heavily in ensuring that everyone is able to achieve fast connections at the busiest times, this capacity will be available to more people at less busy off-peak times like during the night when the majority of customers are asleep.

When a service is uncongested at off-peak times, you’ll be more likely to experience the maximum speed your broadband connection can achieve, while at the busiest times you may see some degree of slowdown.

How much slowdown your service suffers at peak times depends on how heavily your provider has invested in network capacity. The most expensive providers that tend to be primarily focused on business and home office users are likely to have more capacity than budget providers that make savings by compromising on capacity to spread it across more customers.

In the consumer market, providers who’ve advertised themselves as ‘truly unlimited’ tend to have invested more in their network capacity to achieve this, although buzzwords can also be used as a marketing ploy by budget providers so also pay attention to factors like ‘up to’ speeds, speed estimates and reviews before signing up.

Another factor to consider is that if your broadband provider mostly handles business connections then their busiest peak period is likely to be during the working day, rather than the more typical evening hours of most consumer broadband.

What 'average speeds' actually mean

Broadband suppliers advertise how fast their packages are using 'average speeds'. These give you a rough idea of what you might get - but no guarantees!

When you see the average speed advertised with a broadband deal, it's referring to the average download speed available to at least 50% of the supplier's customers during peak hours, from 8-10pm for residential users and 12-2pm for business users.

While this is a lot more useful than the old rules, which allowed ISPs to advertise an 'up to' speed so long as it was attainable by just 10% of customers, it still doesn't give you any guarantees as to what speed you'll actually get. An average, by definition, means that some users will beat it, and others will fall short. And if you're in a very remote area you could fall well short.

Ofcom figures for 2018 show that 61% of users in urban areas had peak-hour speeds of 30Mb or higher, compared to 44% in rural areas. A third of rural users had to settle for speeds below 10Mb.

Use our Speed Test tool to see what speed you're getting right now, and check out our guide on how to speed up slow broadband for some tips on improving it.

Estimated speeds and speed guarantees

To help bring clarity to the speed issue, many of the major broadband providers have signed up to Ofcom's voluntary code of practice for broadband speeds.

Brought into play from March 2019, the code has three main provisions:

  1. When you sign up to a new broadband service you should be given an accurate speed estimate. This should show the speed you can expect during peak hours, and should take into account slowdown for network congestion during this period.
  2. You will be given a minimum guaranteed speed.
  3. If your speed falls below the minimum guarantee your provider must fix it within 30 days of being informed of the problem. If they don't you'll have the right to exit your contract without penalty. This right also covers bundled products purchased at the same time, including pay-TV services.

The code is supported by BT, EE, Plusnet, Sky, TalkTalk, and Virgin Media, who account for around 95% of all broadband users. It should ensure there are no more nasty surprises when you take on a new deal. You'll know exactly what speed you can expect to get - and whether it will be faster or slower than the advertised average speed - and there's a commitment from the provider to fix your connection within a month if the speed falls below the minimum level they have agreed. The abilty to quit a contract without penalty also takes away some of the risk of switching providers.

Ofcom suggest that you could ask for a discount instead of leaving your contract, if the situation arises. You might not always be able to get faster speeds by switching providers. Use our postcode checker to see what other broadband deals are available in your area.

Upload speeds

Most of the information above refers to download speeds - how quickly you can get information from the Internet to your devices - but it's important to consider uploading as well.

How upload speed works

Upload speed refers to the rate at which information can be transmitted from your devices to sites and servers on the Internet. This affects things like cloud backup/sync of files, sending photos to sharing services or videos to sites like YouTube or Facebook.

Uploading tends to be seen as less important than how quickly you can download or stream content from the Internet, but as more and more services move on to the cloud, and more of us share videos with our friends and family, or with the world, this is becoming increasingly important.

Broadband technologies have limited capacity that's split between downloading and uploading. As download speeds tend to be seen as most important for home users, and are what’s advertised to sell broadband by speed, home broadband is usually split to give far more of the share to download.

Different types of broadband

Upload speeds tend to be particularly low on entirely phoneline broadband services where a connection with an 11Mb average speed will typically only be 1Mb. In rural and remote areas that are still on older services, upload speeds can be as little as 0.25Mb. The consolation in the case of phoneline broadband is that the frequencies used for upload speed tend to be those closest to voice, so they don't tend to slow down with distance from the telephone exchange, so a service getting the slowest supported download speed will still likely be enjoying the full supported upload speed.

For fibre to the cabinet services there are different upload speeds available. The slower package with an average download speed of around 35Mb will hit around 9Mb for the average upload speed. The faster 67Mb (or so) option will have an upload speed of around 18Mb. As always, these are averages, so you may do better or worse in practice.

For Virgin Media you get 3Mb on the slowest VIVID 50 deal (50Mb average download speed), rising to 21Mb on the VIVID 300. These are a little lower by ratio than you'll get from most other providers.

The kings of upload speeds are fibre to the home providers like Gigaclear and Hyperoptic. They offer symmetric services, where the download and upload speeds are the same. They both have average upload speeds of an incredible 900Mb on their fastest plans. The downside is that they're only available to around half a million homes as of mid-2019.

Speed estimates

Unfortunately most price comparison don't yet give estimates for upload speed. However, the Ofcom voluntary code of practice, requiring speed estimates at sign up and efforts to fix the speed or let you out of your contract if real use doesn’t match the estimate, also applies to upload speeds.