Unit

Size

What it means

Bit (b)

1 or 0

Short for “binary digit”, after the binary code (1 or 0) computers use to store and process data—including text, numbers, images, videos, etc.

Byte (B)

8 bits

Enough information to create a number or an English letter in computer code. It is the basic unit of computing.

Kilobyte (KB)

1,000, or 210, bytes

From “thousand” in Greek. One page of typed text is 2KB.

Megabyte (MB)

1,000KB, or 220, bytes

From “large” in Greek. The MP3 file of a typical song is about 4MB.

Gigabytes (GB)

1,000MB, or 230, bytes

From “giant” in Greek. A two-hour film can be compressed into 1-2GB. A 1GB text file contains over 1 billion characters, or roughly 290 copies of Shakespeare’s complete works.

Terabyte (TB)

1,000GB, or 240, bytes

From “monster” in Greek. All the catalogued books in America’s Library of Congress total 15TB. All the tweets sent before the end of 2013 would approximately fill an 18.5TB text file. Printing such a file (at a rate of 15 A4-sized pages per minute) would take over 1200 years.

Petabyte (PB)

1,000TB, or 250, bytes

The NSA is reportedly analyzing 1.6 per cent of global Internet traffic, or about 30PB, per day. Continuously playing 30PB of music would take over 60,000 years, which corresponds to the time that has elapsed since the first Homo Sapiens left Africa.

Exabyte (EB)

1,000PB, or 260, bytes

1EB of data corresponds to the storage capacity of 33,554,432 iPhone 5 devices with a 32GB memory. By 2018, the total volume of monthly mobile data traffic is forecast to be about half of an EB. If this volume of data were stored on 32GB iPhone 5 devices stacked one on top of the other, the pile would be over 283 times the height of the Empire State Building.

Zettabyte (ZB)

1,000EB, or 270, bytes

It is estimated that in 2013, humanity generated 4-5ZB of data, which exceeds the quantity of data in 46 trillion print issues of The Economist. If that many magazines were laid out sheet by sheet on the ground, they would cover the total land surface area of the Earth.

Yottabyte (YB)

1,000ZB, or 280, bytes

The contents of one human’s genetic code can be stored in less than 1.5GB, meaning that 1YB of storage could contain the genome of over 800 trillion people, or roughly that of 100,000 times the entire world population.