Bits and bytes terms

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In general, spell out bit and byte terms on the first mention unless:

  • Your audience is familiar with the abbreviation.
  • You’re working on UI text.

In those cases, or after you’ve spelled out the term on the first mention, it’s OK to use abbreviations for -bit or -byte terms. Use abbreviations only with numbers in specific measurements, such as 128 TB.

  • Insert a space between the abbreviation and the numeral, or hyphenate if the measurement modifies a noun.
    Examples
    512 gigabytes (GB) of RAM
    From 1 GB to a maximum of 2 GB
    23 MB/day
    up to 2 terabytes of physical memory with 8 terabytes of address space
    200 MB of available hard-drive space
    a 650-MB limit

  • In measurements, when the unit of measure isn't abbreviated, use the singular form of the unit of measure when the number is 1. Use the plural form for all other measurements.
    Examples
    0 megabytes
    0.5 megabytes
    1 megabyte
    15 megabytes

  • Use of to add a modifier to a measurement used as a noun.
    Example
    The operation requires 200 MB of available hard-drive space.

  • Use commas in numbers that have four or more digits, regardless of how the numbers appear in the UI.
    Example
    1,024 MB

Term Abbreviation Usage
bits per pixel bpp
bits per second bps Don't use as a synonym for baud. See Units of measure term collection for information about baud.
byte None Don't abbreviate, unless in UI.
exabyte EB Don’t use E, E byte, or EByte.
gigabit None Don’t abbreviate, unless in UI.
gigabits per second Gbps Don't spell out as Gb per second.
gigabyte GB Don’t use G, G byte, or GByte.
kilobit None Don’t abbreviate, unless in UI.
kilobits per second Kbps Don't spell out as KB per second.
kilobyte KB Don't use K, K byte, or KByte.
kilobytes per second KBps Don't spell out as KB per second.
megabit None Don’t abbreviate, unless in UI.
megabits per second Mbps Don't spell out as Mb per second.
megabyte MB Don’t use M, meg, M byte, or MByte.
megabytes per second MBps Don't spell out as MB per second.
petabyte PB Don’t use P, P byte, or PByte.
terabyte TB Don’t use T, T byte, or TByte.
zettabyte ZB Don’t use Z, Z byte, or ZByte.