yobibyte (YiB)

Contributor(s): Stacey Peterson

A yobibyte (YiB) is a unit of measure used to describe data capacity as part of the binary system of measuring computing and storage capacity. The prefix yobi was created along with several others as part of the binary capacity measurement system, which is based on powers of two. One yobibyte equals 280 or 1,208,925,819,614,629,174,706,176 bytes.

The International Electrotechnical Commission (IEC) came up with binary system prefixes -- kibi, mebi, gibi, tebi, pebi and exbi -- in 1998. It added the zebi and yobi prefixes in 2005. Before the binary prefixes were created, computing and storage capacity was measured using the metric prefixes of the International System of Units. The SI prefixes, which include kilo, mega, giga, tera, peta, exa, zetta and yotta, are also referred to as the decimal system of prefixes.

Before the advent of the binary prefixes, the SI prefixes were used to refer to both the decimal system's power-of-10 multipliers and the binary system's power-of-two multipliers. As the SI prefixes were being used to refer to measurements in both the decimal and binary multiplier systems, context had to be used to determine which system was being referred to when the term yottabyte (YB) appeared. That term could refer to either 1024 (1,000,000,000,000,000,000,000,000) bytes or 280 (1,208,925,819,614,629,174,706,176) bytes.

Today, the system used often depends on what discipline or industry the speaker or writer works in. The power-of-10 metric prefixes are mostly used in communications, electronics and physics, while the power-of-two binary prefixes are frequently used in IT discussions about data and storage capacity.

What yobibytes are used for

Data storage capacity used to be significantly smaller than what it is today, so using the same prefixes to refer to the two different multiplier systems wasn't a big problem.

For instance, back in the early days of computing, storage capacity was calculated mostly in terms of kilobytes and megabytes. One kilobyte (KB) of data storage equaled 1,000 bytes using the power-of-10 system. When using the power-of-two system, 1 KB of data equaled 1,024 bytes. The 24-byte, or 2.4%, difference between the two systems was small enough to be considered negligible. However, as storage capacity has grown over the years, the difference between the numbers generated by the two capacity measurement systems has been magnified.

Using the decimal power-of-10 system, a terabyte (TB) of data equals 1,000,000,000,000 bytes. Alternatively, a terabyte of data using the binary power-of-two system equals 1,099,511,627,776 bytes. The nearly 100 billion-byte, or 10%, difference is a significant and can't be ignored. At even higher levels of capacity, such as with yottabytes of data, the differences in the numbers the two measurement systems generated are even greater.

This video from TechQuickie looks at why the
capacity of HDDs is smaller than advertised.

One problem was particularly troublesome when the same prefixes were used to describe measurements in both systems. Hard disk drive (HDD) manufacturers used the decimal system when they labeled the capacity of their HDDs. Operating system (OS) vendors, on the other hand, often reported computer memory and data storage capacity using the binary system. But both sets of vendors used the same prefixes. That discrepancy was confusing to customers, who would buy a new hard drive labeled using the decimal system as having, say, 100 gigabytes (GB) of capacity. But when they got it home and put it in their computer, the OS, using the binary system of measurement, would say that it had only 93.13 GB of capacity. That left customers unhappy because it appeared that nearly 7 GB of capacity had disappeared before they had even used the HDD.

The development of the IEC binary system prefixes aimed to eliminate this confusion. In the example above, the OS vendor would have used the binary prefix instead of the decimal system, reporting 93.13 gibibytes (GiB) instead of 93.13 GB of capacity. By using the new prefixes, the OS would let consumers know it was using a different measurement system from the HDD manufacturer.

Binary data and decimal data measurement systems

The IEC had good intentions with the new prefixes. However, they aren't being widely used, and, as a result, haven't solved the capacity measurement problem. Academics, technical writers and open system developers are mostly using the binary prefixes, but they generally aren't used in commercial settings.

How large is a yobibyte?

A yobibyte is the largest unit of measure in the binary measurement scale. The following binary data capacity measures are:

  • A byte -- YiB is equal to 1,208,925,819,614,629,174,706,176 bytes.
  • A kibibyte (KiB) -- a YiB is equal to 1,180,591,620,717,411,303,424 KiB.
  • A mebibyte (MiB) -- a YiB is equal to 1,152,921,504,606,846,976 MiB.
  • A gibibyte -- a YiB is equal to 1,125,899,906,842,624 GiB.
  • A tebibyte (TiB) -- a YiB is equal to 1,099,511,627,776 TiB.
  • A pebibyte (PiB) -- a YiB is equal to 1,073,741,824 PiB
  • An exbibyte (EiB) -- a YiB is equal to 1,048,576 EIB
  • A zebibyte (ZiB) -- a YiB is equal to 1,024 ZiB

Neither the EIC nor the SI has named a unit of measure greater than either a yobibyte or yottabyte. The prefix bronto has been suggested as the next possible unit following the yottabyte and representing 1027, but has not been officially adopted. Likewise, the prefix geop has been suggested to represent 1030 but hasn't been officially adopted. No equivalent binary system prefixes have been suggested.

What yobibytes measure

There is nothing in use that can be measured by a yobibyte. The U.S Intelligence Community Comprehensive National Cybersecurity Initiative Data Center run by the National Security Agency at Camp Williams near Bluffdale, Utah, is one of the biggest data centers in the world. It was reported to have a storage capacity from three EB to 12 EB when construction was completed in 2014.

Data volumes continue to explode, however, so it's only a matter of time before yottabytes and yobibytes become more common. According to IDC, the global datasphere will grow to 163 zettabytes by 2025.

In 2011, the Atlantic reported backup and cloud storage vendor Backblaze had estimated that a million data centers would be required to accommodate a yottabyte of data. A yobibyte would require significantly more data centers.

In his book Word Spy, Paul McFedries said that it would take approximately 86 trillion years to download a 1 YB file. Given that a yobibyte is 209 sextillion more than a yottabyte, it will take 104 trillion years to download a yobibyte.

Yobibyte vs. yottabyte and zebibyte

As previously mentioned, one yobibyte is equal to 280 1,208,925,819,614,629,174,706,176 bytes, and one yottabyte is equal to 1024 or 1,000,000,000,000,000,000,000,000 bytes. A yobibyte is a bit more than 1.21 YB.

Binary system of measurement chart

A yobibyte equals 1,024 ZiB. To do the conversion, divide the 1,208,925,819,614,629,174,706,176 bytes that make up a yobibyte by the number of bytes in a zebibyte, or 1,180,591,620,717,411,303,424. That gives you 1,024 ZiB.

Converting yobibytes

Going up the scale of prefixes in the binary system of measurement, each consecutively higher prefix has 210, or 1,024, times the number of bytes of the prefix before. A yobibyte is 1,024 times larger than a zebibyte in terms of bytes. A zebibyte is 1,024 times larger than an exbibyte. And an exbibyte is 1,024 times larger than a pebibyte and so on.

  • Converting yobibytes to gigabytes: Divide a yobibyte's 1,208,925,819,614,629,174,706,176 bytes by the 1 billion bytes in a gigabyte to get the number of gigabytes in a yobibyte. It comes to 1,208,925,819,614,629 gigabytes.
  • Converting yobibytes to terabytes: Divide a yobibyte's 1,208,925,819,614,629,174,706,176 bytes by the 1 trillion bytes in a terabyte to get the number of terabytes in a yobibyte. It comes to 1,208,925,819,615 terabytes.
This was last updated in September 2018

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