Today I would like to demystify the kilobyte issue and explain why there are sometimes large differences between an advertised devices’ capacity, and the capacity that same device displays in Windows and other operating systems. I will also explain the difference between kilobyte, kilobit and kibibyte.

If you just want to convert a kilobyte to another value (megabyte, megabit, gigabyte, gigabit etc) then use the Byte Converter further below, but if you want to learn about bits and bytes and their multiples, then read on!

Contents

1. Kilobytes, Megabytes, Gigabytes
   • Kilobyte (Binary, JEDEC)
   • Kilobyte (Decimal, Metric)
   • Kibibyte (Binary, IEC)
   • Kilobit (Decimal, JEDEC)
   • Kilobit / kibibit (Binary, JEDEC & IEC)
2. Download conversion charts (PDF)
3. Bit, Byte, Kilobyte Converter
4. Conclusion

Kilobytes, megabytes, gigabytes

First, let’s get some things out-of-the-way. Bits, bytes and their multiples is a very confusing issue, and I have tried very hard to lay everything out in an as-easy-to-understand way however, this isn’t easy, it’s hard (at first anyway). It certainly doesn’t help when manufacturers use the wrong terms to describe their product capacity (not kidding). I would describe the situation as a dog’s breakfast, but hey, that’s just my opinion 🙂

Now let’s get straight into the different definitions of a kilobyte, which varies according to the standard being used.

Kilobyte (Binary, JEDEC)

A Binary kilobyte is a digital information unit that is a multiple of a byte, specifically: 1 kilobyte (KB) == 1024 bytes (B). In the Metric system, kilo means 1000, so using the term "kilo" in this context has caused much confusion. It gets even more confusing when hardware manufacturers of storage (hard drives/optical discs/optical drives/flash storage, except RAM) and data communications (networking and other data rates) actually use a different methods to calculate the storage capacity or speed of their products (they use Decimal kilobytes and kilobits, more on this later).

Kilobyte (Decimal, Metric)

Next we have to the Decimal kilobyte which consists of 1000 bytes, specifically: 1 kilobyte (kB) == 1000 bytes (B) and used for data storage (hard drives, flash drives and optical discs etc) and sometimes data communication rates (networking). This is the reason you can buy a USB flash drive advertised as having a 64GB (gigabyte) storage capacity, but shows up in Windows and other operating systems as having only 59.6GB. This is because the manufacturer measures data capacity in 1000 byte blocks (Decimal), however your Windows or other operating system measures the same device using 1024 byte blocks (Binary) hence the smaller size.

Kibibyte (Binary, IEC)

Now to clear up the confusion between a Binary (1024 byte) and a Decimal (1000 byte) kilobyte, the IEC enacted standards with new names for all Binary prefixes for 1024-byte-kilobytes, which replaces the term kilobyte with kibibyte, megabyte with mebibyte, gigabyte with gibibyte, and so on (see table below). These changes are in the hope that we will all refer to a Decimal kilobyte (1000 bytes) as a kilobyte, and the Binary kilobyte (1024 bytes) as a kibibyte. This is in unison with the Metric System where the term "kilo" means 1000.

Kilobit (Decimal, Metric)

Next we have the Decimal kilobit which consists of 1000 bits of digital information and is most often used to express data communication rates, as in networking. For example: an ADSL line speed is expressed as 1500kbps, which means the connections’ capacity is 1500 kilobits-per-second. The same ADSL connection can also be expressed as being 1.5Mbps which means 1.5 megabits-per-second. Please note that a kilobit is in no way comparable to a kilobyte and it’s best not to confuse the two. A kilobyte actually consists of 8192 bits because a kilobit (Metric) has 1000 bits.

Kilobit / kibibit (Binary, JEDEC / IEC)

Finally we have the Binary kilobit (JEDEC) or kibibit (IEC) which consists of 1024 bits of digital information and is most often used to express CPU cache and RAM memory capacities. As with the 1000-bit-kilobyte vs 1024-byte-kilobyte issue, the IEC enacted new names for Binary kilobits and renamed them kibibits, mebibits, gibibits etc in the hope we will now refer to a kilobit as consisting 1000 bits, and a kibibit as consisting of 1024 bits. Please also note that some chip/memory manufacturers still use the Metric prefixes when referring to Binary multiples, further confusing consumers.

Bit, byte, kilobyte conversion charts (PDF)

You might want to download and print these charts for your reference etc.

Byte Converter

Enter the value you want to convert in the proper field, such as: If you wanted to convert 1 binary megabyte into decimal kilobytes, enter 1 into the megabyte/mebibytes field in the middle column (3rd down), click the Calculate button, and the result will be in the right column, 2nd down (1048.576kB).

Conclusion

It can take a few light-bulb moments to fully grasp the kilobyte issue, but if you’re still stuck then read over this article again or perhaps visit some of the links below for further information. If after doing all that you’re still stuck, just email me and I’ll help you out.

Cheers!

Wikipedia links

• Bit at Wikipedia
• Byte at Wikipedia
• Kilobyte at Wikipedia
• Kilobit at Wikipedia
• Metric at Wikipedia
• IEC at Wikipedia
• JEDEC at Wikipedia

Other links

• Kilobytes, Megabytes, Gigabytes at Stanford
• Size comparisons of common data at ComputerHope