Zettabyte – the storage capacity unit explained

External hard drives, USB sticks, memory cards or CDs – the hardware for storing data is diverse. To make the right selection, com­pat­i­bil­i­ty with other devices and storage capacity are crucial. However, despite dif­fer­ences in the in­di­vid­ual hardware, their de­vel­op­ment is similar. Although devices continue to decrease in size, their storage ca­pac­i­ties are in­creas­ing. Compact, external hard drives now usually store one or more terabytes of data and have become more af­ford­able for private users too. At the same time, the quantity of data used worldwide in the private and com­mer­cial sectors continues to grow.

The terabyte tends to be the highest storage capacity unit of common data carriers we encounter on a regular basis. It is followed by the petabyte, exabyte, and zettabyte, which remains largely unknown among the average users. Yet, un­der­stand­ing these data quan­ti­ties is worth it. After all, the zettabyte now rep­re­sents the quantity of all data in use globally. We explain what a zettabyte is and how it is converted into other units.

The zettabyte consists of two terms: zetta and byte. By defining these terms, the meaning of a zettabyte can be easily deduced. A byte consists of 8 bits. A bit describes the smallest possible in­for­ma­tion unit that can adopt one of two states: 0 or 1. This results in a total of 256 (2⁸) different states for one byte. One byte can be used to store a character in binary form.

A text document requires very little storage space compared to other data. Due to the small amount of data, prin­ci­pal­ly it’s possible to specify this in bytes. However, this unit is too small for external storage devices, videos, or music. For this reason, there are numerous multiples of a byte to indicate larger data quan­ti­ties and storage ca­pac­i­ties in a readable number.

“Zetta” is a so-called decimal prefix. The meaning of this prefix is defined in the in­ter­na­tion­al standard system. Zetta therefore always stands for 10²¹. A zettabyte cor­re­sponds to 10²¹ bytes. That’s 1,000,000,000,000,000,000,000 bytes (or one trillion bytes).

But computers don’t use the decimal system for their cal­cu­la­tion. Instead, they use the binary system, which is based on 2. One zettabyte thus cor­re­sponds to 2⁷⁰ = 1,180,591,620,717,411,303,424 bytes. The binary prefix reserved for this size is “Zebi”, the correct des­ig­na­tion is “Zebibyte”. However, binary prefixes are not yet well-es­tab­lished.

The unit byte and its multiples indicate storage ca­pac­i­ties. For example, kilobytes are commonly used for text documents, megabytes for image files, and gigabytes for video files. But bits of in­for­ma­tion are also common in everyday life. Users know about internet speeds such as 100 Mbit/s (megabits per second). That’s because for trans­mis­sion rates, the unit bit is commonly used. Basically, bytes can always be converted into bits. Zettabits are also cal­cu­la­ble and indicate cor­re­spond­ing transfer rates. In contrast to zettabytes, the use of zettabits is currently neither necessary nor common.

The memory unit zettabyte is suitable to designate the capacity of data in use globally. Day to day, however, we only encounter smaller units of in­for­ma­tion. The following table shows the relation of different storage units and explains how they’re converted.

The term “zettabyte era” describes two different de­vel­op­ments. On the one hand, it relates to the general rise in digital data used worldwide. On the other hand, the term indicates the point in time when global data usage reached the order of magnitude of zettabytes. This gives rise to two possible be­gin­nings for the zettabyte era. As early as 2012, the total number of digitized data used worldwide exceeded one zettabyte. According to al­ter­na­tive de­f­i­n­i­tions, this era didn’t actually start until 2016. This year, global data traffic via the Internet alone exceeded this data volume. It is estimated that the amount of data will grow to 175 zettabytes by 2025.