zebibyte (ZiB)

What is a zebibyte (ZiB)?

A zebibyte (ZiB) is a unit used to measure computing and storage capacity.

The prefix zebi was created with several others as part of the binary digital capacity measurement system, which is based on powers of two. One zebibyte equals 2⁷⁰ or 1,180,591,620,717,411,303,424 bytes.

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

Zebibyte in data storage

Before the binary prefixes were developed, the SI prefixes were used to refer to both the power-of-10 multipliers of the decimal capacity measurement system and the power-of-two multipliers of the binary system. The only way to tell which system was being referred to when the term zettabyte (ZB) appeared was to consider the context it was being used in. That term could refer to either 10²¹ (1,000,000,000,000,000,000,000) bytes or 2⁷⁰ (1,180,591,620,717,411,303,424) bytes.

Today, which system is used often depends on the discipline or industry. The power-of-10 decimal or metric prefixes are mostly used in the communications, electronics and physics fields, while IT usually prefers the power-of-two binary prefixes.

History of the term

In the early days of computing, data storage capacity was significantly smaller than what it is today. When storage capacity was calculated mostly in kilobytes and megabytes, it wasn't a big problem to use the same prefixes to refer to the two different multiplier systems. The differences between the numbers generated by the two systems of measurement were negligible.

For example, 1 kilobyte (KB) of data storage equals 1,000 bytes using the power-of-10 decimal system. And 1 KB of data using the power-of-two binary system equals 1,024 bytes. The difference of 24 bytes is small enough to be ignored. But data and storage capacity have grown since those early years, and bigger numbers have magnified the difference between the two measurement systems.

Many enterprises are now dealing in terabytes (TB) and even petabytes of data. Using the power-of-10 decimal system, 1 TB of data is equivalent to 1,000,000,000,000 bytes, while 1 TB of data using the power-of-two binary system equals 1,099,511,627,776 bytes. That's a difference of nearly 100 billion bytes, which can't be ignored. At even higher levels of capacity, such as zettabytes and yottabytes, the differences between the two measurement systems are even greater.

When the same prefixes described measurements in the decimal and binary systems, one problem in particular cropped up. Hard disk drive manufacturers labeled the capacity of their HDDs using the decimal system. Operating system (OS) vendors didn't follow suit, however, and frequently reported data storage capacity using the binary system. But the same prefixes were used by both sets of vendors, leaving customers confused.

A customer might buy an HDD labeled using the decimal system as having 100 gigabytes (GB) of capacity. But when that person put the HDD in their computer, the OS -- using the binary system of measurement, but the same SI prefix -- would report that it had only 93.13 GB of capacity. The customer was rightfully unhappy because it appeared that nearly 7 GB of capacity had disappeared before the HDD was even used.

The development of the IEC standard for the binary system prefixes was meant to eliminate this confusion. Once the new prefixes were in place, the OS vendor in the previous example would have used the binary system's gibibyte instead of the decimal system's gigabyte, and would have reported 93.13 GiB instead of 93.13 GB of capacity. The use of the binary prefixes would let the customer know that the OS vendor was using a different measurement system from the hard drive manufacturer.

The IEC's intentions were genuinely good in developing the new prefixes. However, they aren't being widely used, and consequently, they haven't solved the data capacity measurement problem. Academics, technical writers and open system developers are those most likely to use the binary prefixes, which generally aren't used in commercial settings.

How large is a zebibyte?

A zebibyte is larger than the following binary data capacity measures:

• A byte.
• A kibibyte (KiB) -- 1 ZiB is equal to 1,152,921,504,606,846,976 KiB.
• A mebibyte (MiB) -- 1 ZiB is equal to 1,125,899,906,842,624 MiB.
• A gibibyte -- 1 ZiB is equal to 1,099,511,627,776 GiB.
• A tebibyte (TiB) -- 1 ZiB is equal to 1,073,741,824 TiB.
• A pebibyte (PiB) -- 1 ZiB is equal to 1,048,576 PiB.
• An exbibyte (EiB) -- 1 ZiB is equal to 1,024 EiB.

A yobibyte is larger than the zebibyte. It's equal to 1,024 ZiB.

The 2022 General Conference on Weights and Measures decided on two new prefixes for data volumes that grow beyond the yottabyte. The ronnabyte is equal to 10 to the 27th power, and the quettabyte is 10 to the 30th power.

What zebibytes measure

There aren't any products or systems in use that have zebibytes of capacity. But given the volume of data growth the world is experiencing, it's only a matter of time before zettabytes and zebibytes become common.

Industry observers in 2009 said 1 ZB of new data had been created that year. Analyst firm IDC has forecast the global data sphere to grow to about 175 zettabytes by 2025.

Zebibyte vs. zettabyte and exbibyte

One zebibyte is nearly 1.81 ZB. A zebibyte equals 1,024 EiB.

To do the conversion, divide the 1,180,591,620,717,411,303,424 bytes that make up a zebibyte by the number of bytes in an exbibyte, or 1,152,921,504,606,846,976. That gives you 1,024 EiB.

Convert zebibytes to terabytes and exabytes

Each consecutively higher prefix in the binary measurement system has 2¹⁰, or 1,024, times the number of bytes of the prefix before. Multiply yobibytes by 1,024 to get zebibytes. Multiply zebibytes by 1,024 to get exbibytes. And multiply exbibytes by 1,024 to get pebibytes, and so on.

Here are some examples of how to convert zebibytes to capacity measures that use the decimal measurement system:

• Zebibytes to terabytes. To convert zebibytes to terabytes, multiply the number of zebibytes in question by the number of bytes in 1 ZiB (1,180,591,620,717,411,303,424) and then divide by the number of bytes in 1 TB (1,000,000,000,000). The answer is the terabyte equivalent of that amount of zebibytes.
• Zebibytes to exabytes. To convert zebibytes to exabytes, multiply the number of zebibytes in question by the number of bytes in 1 ZiB (1,180,591,620,717,411,303,424) and then divide by the number of bytes in 1 EB (1,000,000,000,000,000,000). The answer is the exabyte equivalent of that amount of zebibytes.

Editor's note: This article was revised in 2023 by TechTarget editors to improve the reader experience.