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When discussing internet connection speeds you will often come across abbreviations for kilobits per second (Kbps) and megabits per second (Mbps). At the simplest level, most people simply know that Mbps is faster than Kbps. However, you may be curious why this is.

Latin and Greek Prefixes

To start with, we will need to become familiar with some common Latin & Greek prefixes. Rather than dealing with the whole etymology of these terms, as some other sites (http://www.jamesshuggins.com/h/tek1/prefixes.htm) have done, I’m going to focus on the meaning of these prefixes. Below is a chart of the most common Latin and Greek prefixes used in computer terminology today.

Tera- trillion (1,000,000,000,000)

Giga- billion (1,000,000,000)

Mega- million (1,000,000)

Kilo- thousand (1,000)

Kilo vs Mega

Some basic conversions show that a kilobyte is 1,000 bytes (or 1/1000^th of a megabyte) and a megabyte is 1,000,000 bytes (or 1,000 kilobytes). In other words, when discussing hard drive storage capacities you could refer to a drive which stores 10,000 kilobytes of data, or simply 10 megabytes. In both cases you would be referring to the same amount of data. By changing the prefix the numbers are easier to understand. This becomes even more obvious when considering that many hard drive can now store terabytes of data. It would be incomprehensible to discuss a drive which stores 2,000,000,000,000 kilobytes instead of simply 2 terabytes.

8 Bits = 1 Byte

This is where it gets complicated, there are eight bits in one byte. This means that Kb and KB are not the same thing. Kb refers to kilobits while KB signifies kilobytes, so 1KB is equal to 8Kb. This is a common confusion when discussing internet connection speeds. Many people are used to saying kilobytes and forget that the Kb in Kbps stands for kilobits.

Data Transmission

Kbps and Mbps are two abbreviations which are commonly used to discuss data transmission rates. Each is dealing with the number of bits which can be transferred per second, but one is scaled in the thousands and the other is in the millions. Kbps stands for kilobits per second while Mbps stands for megabits per second. There is no standard discussion of kilobytes per second (KBps) or megabytes per second (MBps) and this is due to difficulties in converting these units. Remember, there are eight bits in one byte. This means that to convert Kbps to KBps you would have to divide by eight. A simple example would be converting 8 Kbps into 1 KBps. However, more commonly measured internet speeds are 28.8Kbps, 56Kbps, 1.5Mbps, and 10Mpbs. Each of those do not convert to KBps or MBps very easily.

Toss it all

I’ve explained Kbps and Mbps so you now have a strong foundation for understanding these terms. The next step is to pull the rug out from under you and explain when these rules change. There are two competing interpretations of the Greek and Latin prefixes described in the first section above. Traditionally, these terms have been used in the base ten number system (the numbers 0 – 10 that we typically use when counting). Computers use base two which is described in more detail by other sites (http://www.jamesshuggins.com/h/tek1/how_big.htm). Counting 0 – 10 like this: 0,1,10,11,100,101,110,111,1000,1001,1010. For this reason the prefixes are defined as shown in the chart below:

Tera- 2^40 (1,099,511,627,776)

Giga- 2^30 (1,073,741,824)

Mega- 2^20 (1,048,57)

Kilo- 2^10 (1,024)