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Bits and bytes explained: how to understand internet speed

Can't tell your bits from your bytes? Read on to learn the difference and figure out what broadband speed you need.
Nick Baker author headshot
Written by Nick Baker, Senior Editor
Updated on 8 October 2024
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Even though people tend to informally refer to them both as 'megs', connection speeds and data sizes are actually measured differently.

The word 'meg' could refer to two very different values: megabits and megabytes. But aren't they the same thing?

Actually, no - there's a big difference between the size of a bit and a byte. A byte is much bigger — eight times bigger to be exact — with eight bits fitting inside every byte. So there are eight megabits (Mb) in every megabyte (MB), and eight gigabits (Gb) in every gigabyte (GB).

In a nutshell: 1MB = 8Mb.

Bits, bytes and broadband speeds

You may be wondering how this relates to you and your broadband speed.

Data sizes are usually measured in 'Bytes' (with a capital B), and broadband speeds are measured in 'bits' (lowercase b). Based on the file size and your connection speed, you can estimate how long it'll take you to download things like film or video games.

When to use bits vs when to use bytes

Files - measured in 'Bytes'

Internet speed - measured in 'bits'

Let's say you find a file online that is 50 megabytes (MB) in size, and you want to download it using your 50 megabits per second (Mbps) broadband connection. This won't take one second; it will take eight times one second because a megabyte is eight times bigger than a megabit.

So in theory - and with a perfectly consistent speed - it should take eight seconds to download.

Before you start reaching for your calculator, try our download times tool. You can enter a file size and broadband speed of your choice and it will show you how long it'll take to download.

Here's an example of how fast you could download certain file sizes.

Download times for different internet speeds

File sizeInternet speedTime to download
5GB50Mbps13min, 20sec
5GB300Mbps2min, 13sec
50GB50Mbps2hr, 13min, 20sec
50GB300Mbps22min, 13sec

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Bits vs bytes: what's the difference?

You can tell the difference between both file type from how it's written in the unit of measurement. A byte is used with an uppercase 'B' and a bit is a lowercase 'b'. If it says MB, all capitals, then it is a megabyte. If it says Mb with a lowercase 'b', then it is a megabit.

There is one exception to this, of course, and it is the symbol for kilobit, which is 'kb', all lowercase. But these file sizes are so small nowadays that you shouldn't really see much of them.

It's easy to figure out based on common sense: an uppercase 'B' is physically larger than a lowercase 'b', and a byte is larger than a bit.

In a nutshell:

  • MB = big B = bigger
  • Mb - small b = smaller

Gigabytes, megabytes and kilobytes explained

While there's a range of different file sizes, most of us only need to know a few different prefixes. Here are the most common ones.

  • KB, MB, GB: A kilobyte (KB) is 1,024 bytes. A megabyte (MB) is 1,024 kilobytes. A gigabyte (GB) is 1,024 megabytes. A terabyte (TB) is 1,024 gigabytes.
  • kb, Mb, Gb: A kilobit (kb) is 1,024 bits. A megabit (Mb) is 1,024 kilobits. A gigabit (Gb) is 1,024 megabits. A terabit (Tb) is 1,024 gigabits.

Don't forget! There are eight bits in a byte, so to translate from one to the other, you can multiply or divide by eight. For example, if you want to transfer 38MB across a 38 Mbps connection, it will take eight seconds.

Is a KB bigger than a MB?

No - a MB (Megabyte) is 1000 times larger than a KB (Kilobyte).

How many KBs are in a GB?

There are one million KBs (Kilobytes) in a GB (Gigabyte). a Gigabyte is 1000 times larger than a Megabyte (MB), which is 1000 times larger than a Kilobyte.

Which is bigger, a MB or a GB?

A GB (Gigabyte) is 1000 times bigger than a MB (Megabyte).

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