What are the minimum room sizes in an HMO?

6.51 square metres for one person over ten, 10.22 square metres for two people over ten, and 4.64 square metres for a child under ten.

Floor space under 1.5 metres in height does not count towards the total, which catches out attic rooms with sloping ceilings.

The licence will state the maximum number of people for each room, and letting a room to more than that breaches the licence. Councils can and do set larger minimums than the national figures, so check the conditions on your own licence rather than the general rule.