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What's the difference between a bit and a byte?

Last updated: 19 April 2021

What's the difference between a bit and a byte?
Is there a difference between bits and bytes or can the two terms be used interchangeably? In this guide we’ll be explaining the difference between the two terms and why it’s useful to know the distinction when looking at your broadband speeds.

Bits and Bytes: Why the confusion?

The problem all starts when people use the term ‘megs’ when referring to both megabits-per-second and megabytes. There’s quite a big difference between the two - both in terms of size, and what kind of measurement they are.

How do bits and bytes differ in size?

A bit is significantly smaller than a byte - there are exactly 8 bits to a byte. Similarly, there are 8 megabits to a megabyte, and 8 gigabits to a gigabyte. So a megabit and a megabyte are two very different sizes - one being 8 times bigger than the other.

Sizes vs Speeds

When we talk about ‘megabytes’, we are using a size measurement to refer to the actual size of a given set of data. ‘Megabits-per-second’ is a speed measurement and refers to the speed of data transfer.

Still confused? An easier way of thinking about it is the difference between distances and speeds. ‘30 miles’ is a distance value. It tells you the ‘size’ between point A and point B. ‘30 miles-per-hour’ is a speed. It tells you how fast an object is travelling.

File Size vs Broadband Speed

The problem is, a megabyte is a common measurement that many of us are used to when measuring the size of data - for example, the size of a file. But when it comes to measuring speeds, they are measured in terms of megabits. This is like measuring distances in miles, but then using yards-per-second to measure speeds.

So when you’re looking at broadband speeds and see or hear the term ‘megs’, they are referring to megabits-per-second - and as you now know, a megabit is 8 times smaller than a megabyte.

Still unsure how many megabits-per-second, or Mbps, you should be looking for when taking out a new Internet contract? Read our guide on what broadband speed do you need.

How long does a file take to download?

If you’re trying to calculate how long it would take you to download a file that is 30 megabytes in size, and you have a 30 ‘meg’ download speed on your broadband, it won’t take one second. It will take eight seconds, because bits are eight times smaller than bytes.

Is your internet connection not achieving these speeds? Read our piece 'Why is my internet so slow?' to troubleshoot why.

How can I tell the difference between bits and bytes?

When looking at data values it’s easy to determine whether a value is being described in megabytes or megabits by looking at how it is written. Megabytes are written in upper case: MB. Megabits are written with the ‘b’ in lower case: Mb. So you will see broadband speeds written as ‘Mbps’ rather than ‘MBps’, and file sizes written as ‘MB’ rather than ‘Mb’.

How do bits and bytes relate to other file sizes?

The same problem is now starting to occur when referring to ‘gigs’. Having a 500 ‘gig’ hard-drive and a 1 ‘gig’ broadband speed are two very different things. Just like the megabit/megabyte confusion, we’re seeing a gigabit/gigabyte confusion.

Here are some other file sizes and their corresponding abbreviations:

  • Kilobyte (KB)
  • Megabyte (MB)
  • Gigabyte (GB)
  • Kilobit (kb)
  • Megabit (Mb)
  • Gigabit (Gb)

And here are how the sizes all relate to each other:

  • 8 bits = 1 byte
  • 1,024 bytes = 1 kilobyte
  • 1,024 kilobytes = 1 megabyte
  • 1,024 megabytes = 1 gigabyte
  • 1,024 gigabytes = 1 terabyte

Some of the best broadband deals come with superfast download speeds of up to 1Gb/s with fibre optic technology, but this isn’t the only factor consider when you compare broadband. You should also think about download limits, with many deals nowadays offering unlimited usage, as well as of course, the price.

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Fergus Cole

Author: Fergus Cole

Fergus is a journalist specialising in the personal finance, energy and broadband sectors. He also has a passion for travel and adventure so tries to make the most of this in any spare time he gets.