Overview: Bitrate and file size

Bitrate, duration and data units connect the amount of encoded media to its storage and delivery requirements.

Bitrate is a rate, while file size is an accumulated amount. Duration connects them, but a varying rate means that one moment's demand need not match the whole file's average. These pages make the units and observation intervals explicit, which helps when estimating storage or comparing a media rate with network capacity.

• Bitrate
  Bitrate measures how much encoded data represents each second of media.

• Bitrate variation
  Bitrate variation describes how the amount of encoded data changes across the running time of a media source.

• Digital media data units
  Bits, bytes, and decimal or binary prefixes express different amounts of media data.

• File size and duration
  Average bitrate and running time provide a practical estimate of a media file's size.