What is bandwidth, and how does it help with broadband?

Bandwidth and broadband are often conflated, so knowing the difference between the two will help to ensure your next broadband deal is suitable for your needs

Monday, 12 October, 2020

The digital world is full of similar-sounding terms which actually have very little in common.

FTTP and HTTP are completely unrelated, while HTTP and HTML share the same HyperText prefix but otherwise describe different processes.

Similarly, the terms bandwidth and broadband are often confused.

Broadband is the term for a type of internet connection, like dial-up. Meanwhile, bandwidth relates to the volume of data which can be piped through a specific connection.

As such, it’s central to the provision of effective (and suitably fast) broadband services.

Distinguishing bandwidth and broadband

Definitions of bandwidth tend to describe the maximum volume of binary bits which can be transferred across an internet connection at any given second.

We explained earlier this year how pretty much everything a computer does involves a vast string of either zeroes or ones.

This includes everything distributed over the internet. YouTube videos, Trello boards, FIFA matches… computers process them all as incalculably large streams of zeroes and ones.

Bandwidth determines how many binary bits can be transmitted in one second, and this is measured in bits per second (bps).

However, because a bit carries such a miniscule amount of information, we tend to group them into millions – megabits, or Mbps.

An 11Mbps internet connection over a phone line can distribute up to 11 million binary bits of data per second. This is the maximum bandwidth that connection can support.

Band’ of brothers

When it comes to online activity, not all data is equal.

Internet service providers prioritise downloads over uploads, on the basis that private individuals spend far more time downloading (consuming) data than uploading (creating) it.

Of course, there are exceptions. A Zoom call is a fairly equitable two-way data exchange, and online gaming requires a lot of information to be sent as well as received.

However, domestic internet connections can be biased in favour of downloads by a ratio of 10:1.

Bandwidth and broadband may be absolutes, but actual speeds are never quite as impressive as they sound.

For instance, a 60Mbps connection can deliver an absolute maximum of 60Mbps in perfect conditions.

In reality, there’s no such thing.

Factors like network congestion, server delays and latency all chip away at those theoretical capacities, slowing down the transfer of each individual bit.

It’s also important to remember connections aren’t always consistent from server to screen.

Data tends to be piped from network servers to local telephone exchanges down fibre optic cables capable of gigabit data transfers.

Yet in many cases, data’s journey is then hobbled by Victorian copper cabling in the phone lines used for ADSL broadband, slowing bandwidth to a relative crawl.

As such, don’t assume advertised bandwidth is entirely reflective of actual connection speeds.

Your chosen ISP’s marketing literature will be far more representative, since advertised speeds have to be achievable in real-world conditions.

Neil Cumins author picture


Neil is our resident tech expert. He's written guides on loads of broadband head-scratchers and is determined to solve all your technology problems!