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What is the difference between a kilobit and a kilobyte?

The difference between kbps and kBps is very often a source of confusion. When we talk about transfer speeds we use a different unit of measure than when we talk about file sizes. The confusion occurs because the two units are abbreviated very similarly. At AccessCom, we make every attempt to use the correct unit of measure. It doesn't mean that mistakes won't occur. Like everyone else, we've used the wrong unit by accident a few times.

Purpose

In this article, we will attempt to explain the difference so that our customers can have a better understanding of the service we provide for them. We also hope this will help to educate our customers and put an end to unrealistic expectations about bandwidth speeds.

kbps vs KBps

A bit is the smallest unit of information. It is the ones and zeroes that make up all information. When we talk about data transfer speeds over the internet, this is the unit of measure we are talking about. A kilobit is 1,000 (one thousand) bits and is abbreviated 1 kbps. One megabit equals approximately 1 million bits (1 Mbps).

A byte is a unit of measure that means 8 bits (1 byte = 8 bits). Data files are typically made up of clusters of data. Each of these clusters contain 8 bits (or 1 byte). Since these clusters (byte) are the smallest unit of useful data in a data file, file sizes are normally described in bytes. Thus, the rate of a file downloaded is often (always) given in bytes per second instead of bits per second. Your program (such as Internet Explorer) doesn't care how fast your internet connection is going. It only cares how fast the file itself is being downloaded. 1 kilobyte is 1,000 bytes but it is also 8,000 bits (1 KBps = 8kbps). 1 megabyte per second download (1MBps is approximately 8.2 megabits (8.192 Mbps). Phew!

It can probably be better illustrated using numbers you may be familiar with. If your ISP promises 2 megaBITs per second (2 Mbps), you'll be able to download files at a theoretical 244 kiloBYTEs per second (244 KBps).

At AccessCom, we sell a lot of T-1's. A T-1 is reliable, old phone technology that transfer at a rate of 1.544 Mbps (megaBITs per second). If you download a file in Internet Explorer you will see the download rate displayed 188 KBps (kiloBYTEs per second).

Note: In reality you won't see files downloading at 188 KBps. You'll more likely see anywhere from 150 KBps to 165 KBps as your maximum download rate. This is due to overhead. Some of your bandwidth is used up by embedded information that describes things like where your data is headed, what kind of data is being transported, priority of your data, etc. This embedded information breaks your file up into packets and when you send a file over the Internet, a lot of other information not related to your file has to be sent along with it to ensure that your file gets where it is going.

Also, your download speed is not just affected by your bandwidth availability but by who you are connecting to. If the server you are downloading a file from has a slower connection than you, then you can only download as fast as the slower connection allows.

Disclaimer

We are aware that some information presented here is not technically accurate to a level of precision that might satisfy an informed person (if you know this already, then why are you reading this?). The purpose of this page is to present this information in a way where people less familiar with computer terms can walk away with a little bit of understanding and clarity as it pertains to their needs for phone and Internet service.