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What's the difference between bits and Bytes?

Bits and Bytes can be confusing, bits per second is used to describe internet speed and bytes is used to calculate a file size.

  • bits are noted using a lower case “b”

  • Bytes are noted using an upper case “B”

For example

8 Mbps (Megabits Per Second) would be used to describe their connection speed and 8 MB (MegaBytes) would be used to show the size of a file they want to download.

A bit is a single digit, the smallest increment of data on a computer. Bits are usually assembled into a group of eight to form a byte.

Why does this matter?

If you want to download an 8MB (MegaByte) file you might expect this to take 1 second on an 8Mb (Megabit) connection.

In reality this will take longer as there are 8 bits in a Byte so it would take 8 times as long (8 seconds) on a perfect 8 Megabit connection.

The table below shows how long different file sizes will take to download on different speeds.

Broadband speeds : bits vs bytes Table

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