Bits and Bytes: What's the Difference?

In order to understand your Internet connection speed and how your computer stores information, you should start with the most basic measurements of data: bits and bytes. Before you read further, don't forget that a “b” (small case b) is a bit, and “B” (upper case B) is a byte, e.g., kb is kilobit and kB is kilobyte.

A bit (b) is the smallest measurement of data that can be stored or transferred on computers and Internet services. Bits store information based on a binary system of 1's and 0's (“bi” means 2, i.e., 2 numbers, 1 and 0). Bits are arranged and stored in sequences that are translated into words, pictures, etc., when you see them on your computer screen.

When you hear the term “bits”, it is usually used to when measure transfer rate, as in downloading from the Internet or an Internet connection speed. For example, “bps” is bits per second, or, the amount of bits that can be downloaded or transferred in a second. When measuring transfer rate for Internet connections, 1 kilobit (kb) = 1000 bits, 1 megabit (mb) = 1000 kilobits. Therefore, if your dial up connection successfully connected at 34.4 kbps, 34.4 kilobits or 34400 bits can be downloaded per second to your computer. If you have a 6000 kbps (or 6 mbps) DSL connection, you can download 6000 kilobits, or 6,000,000 bits per second.

A bit rate is the rate at which a certain number of bits (or kb or mb) can be streamed or downloaded per second. You will usually hear about “bit rates”in relation to audio and video streaming from the Internet. A higher bit rate means that the quality of the streaming will be higher, but it also requires a faster Internet connection to stream in real time. For example, to watch a video that has a bit rate of 240kbps, You would want to have a connection that is at least slightly faster to watch the video without interruptions.

A byte (B) is 8 bits. As you read earlier, bits store information based on a binary system and are arranged and stored in sequences, or bytes. Strings of bytes make up documents, images, commands for your computer, etc. Most sizes of files, programs, and capacities of drives, etc, are measured in bytes, kilobytes, megabytes (megs), and gigabytes (gigs).

When describing capacity, like file size or storage, bytes are measured by the binary system that bits use to store information. Therefore, “kilo” = 1,024 (or, 2^10). A kilobyte (kB) is 1,024 bytes, and a megabyte (mB) is 1,024 kilobytes. A gigabyte (gB) is 1,024 megabytes, etc.

Here are some examples of those numbers in relation to your computer. A typical Microsoft Word document is about 30 kB in size. An image is typically about 100 kB, depending on the size and format. When you save that document or image to your computer, it takes up 30 kB or 100 kB of your computers storage space. A CD typically has about 700 mB (or 716,800 kB) of storage space. Most hard drives on personal computers are now sold with a capacity of 500 gig (or 524,288,000 kB).

To review, 1 byte is 8 bits. An Internet connection (transfer rate, download/upload speed) is measured in bits, and 1 kilobit is 1,000 bits. Storage capacity (drive/disk space and file sizes), it is measured in bytes, and 1 kilobyte is 1,024 bytes.