Data Storage
Part 4 - Is the Kilobyte 1000 Bytes or 1024 Bytes?
Due to confusion that has been caused by us the "Greek" prefixs for Metric/SI units, and Data/Information processing, In 1999, the International Electrotechnical Commission (IEC) published an ammendment to its standard on Letter Symbols to be used in Electric technology. This Standard (60027) had ammendments made to Part 2, on binary prefixes has resulted in some public interest in the standard and is still being widely discussed in the computer community, as it attempts to finally settle the confusion about whether a kilobit corresponds to 1000 bits or 1024 bits.
As a result, the standard approved the use of new prefixes: kibi-, mebi-, gibi-, tebi-, pebi-, exbi-,. to be used in specifying binary multiples of a quantity. The names come from the first two letters of the original SI prefixes followed by bi which is short for "binary". It also clarifies that, from the point of view of the IEC, the SI prefixes only have their base-10 meaning and never have a base-2 meaning.
In 2005, Another ammendment was made ti include zebi- and yobi-, thus matching all standard SI prefixes with their binary equivalences
Over the last few years, the use of the new binary Prefixes has become more common, and many organizations, like CIPM, and IEEE have decided to adopt these standards
Why is this Important for me??
The importance is in the fact, that as this standard gets adopted more, you will be required to use the proper prefix. Already many sites are using the binary prefix.
The other important fact is when it comes to Storage and Capacity, the difference between the two can have quite an impact!
- Memory, file sizes, and most data limitations will be in binary
- Marketting of sizes will use the Metric/SI system for Things like "Terabyte Disk Capacity", and "MegaPixel", and "Megabit transfer".
- You need to realize how significant these differences are when planning for Capacity!
The Reference Table
The table below will give sizes for Binary, and Decimal values (and their proper Name/Symbols) and the Percentage Difference (% diff)
| Name - Symbol |
Metric (Marketting) Value |
Binary ( * REAL * ) Value |
%Dif |
| Decimal (Metric/SI) |
Binary (IEC) |
| kilo - k |
kibi - Ki |
103 = 1 KB = 1,000 B |
210 = 1 KiB =1,024 B |
2.4 % |
| Mega - M |
Mebi - Mi |
106= 1 MB = 1,000,000 B |
220= 1 MiB = 1,048,576 B |
4.86 % |
| Giga - G |
Gibi - Gi |
109 = 1 GB = 1,000,000,000 B |
230 = 1 GiB = 1,073,741,824,B |
7.37 % |
| Tera - T |
Tebi - Ti |
1012 = 1 TB = 1,000,000,000,000 B |
240 = 1 TiB = 1,099,511,627,776 B |
9.95% |
| Peta - P |
Pebi - Pi |
1015 = 1 PB = 1,000,000,000,000,000 B |
250 = 1 PiB = 1,125,899,906,842,624 B |
12.6 % |
| Exa - E |
Exbi - Ei |
1015 = 1 EB = 1,000,000,000,000,000,000 B |
250 = 1 EiB = 1,152,921,504,606,846,976 B |
15.3 % |
| Zetta - Z |
Zebi - Zi |
1015 = 1 ZB = 1,000,000,000,000,000,000,000 B |
250 = 1 ZiB = 1,180,591,620,717,411,303,424 B |
18.1 % |
| Yotta - Y |
Yobi - Yi |
1015 = 1 YB = 1,000,000,000,000,000,000,000,000 B |
250 = 1 YiB = 1,208,925,819,614,629,174,706,176 B |
20.9 % |
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