In the United Kingdom, the boundary commissions are non-departmental public bodies responsible for determining the boundaries of parliamentary constituencies for elections to the House of Commons. There are four boundary commissions: one each for England, Scotland, Wales and Northern Ireland.

Each commission comprises four members, three of whom take part in meetings. The speaker of the House of Commons chairs each of the boundary commissions ex officio but does not play any part in the review, and a High Court judge is appointed to each boundary commission as deputy chair.

The boundary commissions, which are required to report every eight years, must apply a set series of rules when devising constituencies. These rules are set out in the Parliamentary Constituencies Act 1986, as amended by the Parliamentary Voting System and Constituencies Act 2011 and subsequently by the Parliamentary Constituencies Act 2020.

Firstly, each proposed constituency has to comply with two numerical limits:

There are a small number of exceptions to the numerical limit on electorate which are specified in the legislation:

Having satisfied the electorate and area requirements, each commission can also take into account a number of other factors:

As these factors can to an extent be mutually conflicting, each commission has discretion on how it applies them. In so doing, each commission aims for a consistent approach within a review.

When a commission publishes its proposals for public consultation, the consultation periods are specified in the legislation: