Data caps: fixed monthly usage limits
A data cap sets a maximum amount of data you can use in a calendar month. Exceed it and depending on the terms you might be charged for additional data, have your speeds severely reduced until the next billing period, or in some older contracts have service suspended. For fixed-line home fibre broadband, hard data caps have become largely obsolete in the UK. Where you are still likely to encounter data caps is on mobile broadband products, 4G and 5G home broadband, and mobile data SIMs. These products operate on shared mobile spectrum with different cost structures.
Fair use policies: traffic management
A fair use policy is different from a data cap. Rather than penalising you for exceeding a total monthly figure, a fair use policy gives providers the ability to temporarily manage or reduce speeds during periods of network congestion for users consuming unusually large amounts of bandwidth at that moment. The aim is to prevent a small number of extremely heavy users from degrading the experience for everyone else on the same local network node.
How to check if a product has a fair use policy
Look in the key facts document or terms and conditions under traffic management policy or network management policy. Reputable providers are transparent about this in their documentation.
What this means in practice
If you are on a standard fixed-line fibre broadband product from a major UK provider with unlimited in the name, you can use as much data as you like for normal household purposes without any issue. If you are on a mobile or 5G home broadband product, check the specific data terms as they vary considerably.
