A byte is a unit of data that typically consists of 8 bits. Historically, this reflected the amount of data required to store an ASCII value to represent one of up to 256 different characters of text.
- A binary kilobyte (KiB) consists of 1,024 bytes ( 210 )
- A binary megabyte (MiB) consists of 1,024 kilobytes, or 1,048,576 bytes ( 220 )
- A binary gigabyte (GiB) consists of 1,024 megabytes, or 1,073,741,824 bytes ( 230 )
- A binary terabyte (TiB) consists of 1,024 gigabytes, or 1,099,511,627,776 bytes ( 240 )
- A binary petabyte (PiB) consists of 1,024 terabytes, or 1,125,899,906,842,624 bytes ( 250 )
- A binary exabyte (EiB) consists of 1,024 petabytes, or 1,152,921,504,606,846,976 bytes ( 260 )
Starting with iOS 11 and Mac OS X 10.6, Apple stopped using binary values and switched to decimals, causing a "megabyte" to report 1,000,000 bytes instead of 1,048,576 bytes, as had been done in the past. This created an illusion of a slight increase in data capacity (memory and storage).
- A decimal kilobyte (kB) consists of 1,000 bytes ( 103 )
- A decimal megabyte (MB) consists of 1,000 kilobytes, or 1,000,000 bytes ( 106 )
- A decimal gigabyte (GB) consists of 1,000 megabytes, or 1,000,000,000 bytes ( 109 )
- A decimal terabyte (TB) consists of 1,000 gigabytes, or 1,000,000,000,000 bytes ( 1012 )
- A decimal petabyte (PB) consists of 1,000 terabytes, or 1,000,000,000,000,000 bytes ( 1015 )
- A decimal exabyte (EB) consists of 1,000 petabytes, or 1,000,000,000,000,000,000 bytes ( 1018 )