Bandwidth cap

A bandwidth cap, also known as a band cap or a data cap, is an artificial restriction imposed on the transfer of data over a network. In particular, it refers to policies imposed by an internet service provider in order to limit customers' usage of their services; typically, exceeding a data cap would require the subscriber to pay additional fees based on whether they have exceeded this limit. Implementation of a bandwidth cap is sometimes termed a fair access policy, fair usage policy, or usage-based billing.

U.S. ISPs have asserted that bandwidth caps are required in order to provide a "fair" service to their respective subscribers. The use of bandwidth caps have been criticized for becoming increasingly unnecessary, as decreasing infrastructure costs had made it cheaper for ISPs to increase the capacity of their networks to keep up with the demands of their users, rather than place arbitrary limits on usage. It has also been asserted that bandwidth caps are meant to help protect pay television providers that may also be owned by an ISP from competition with over-the-top streaming services.

Generally, each user of a network is expected to use high speed transmission for a short time, for example to download a megabyte web page in less than a second. Continuous usage, such as when sharing files or streaming videos can seriously impair service for others. In DSL, where the core network is shared but the access network is not, this concept is less relevant. However, it becomes more relevant in cable internet, where both the core network and the access network are shared, and on wireless networks, where the total network bandwidth is also relatively narrow.

In 2016, U.S. provider Comcast offered a service plan with a data cap of 1 terabyte. At contemporary data consumption rates, each member of a family of four would need to separately watch 100 movies in a month to approach the cap. In that case, typical data usage habits would not exceed that cap.

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