Minimum Room Size Calculator — NDSS and Housing Act Standards

Under the Nationally Described Space Standard (NDSS), a single bedroom must be at least 7.5 m² and at least 2.15 m wide. Under the Housing Act 1985 Space Standard (s.326), a room under 4.65 m² (50 sq ft) cannot be counted as a sleeping room at all, and a room of 4.65-6.50 m² (50-69 sq ft) counts for only 0.5 of a person (a child under 10).

The NDSS requires a double or twin bedroom to be at least 11.5 m². The first double or twin bedroom must be at least 2.75 m wide; every other double or twin need only be at least 2.55 m wide. This allows space for a double bed (1350 x 1900 mm), bedside tables, a wardrobe and a desk or dressing table. Under the Housing Act 1985 Space Standard, a room must be at least 10.22 m² (110 sq ft) to count for the full 2 persons.

The NDSS is not automatically mandatory. It is a nationally recognised standard that local planning authorities can choose to adopt through their local plan policies. Once adopted locally, it becomes a condition of planning permission for new dwellings. Many London boroughs and major cities have adopted NDSS. Check with your local planning authority to see if it applies in your area.

The Housing Act 1985 sets two overcrowding standards. The Room Standard (s.325): two persons of opposite sex aged 10 or over should not have to share a sleeping room (unless they are a couple). The Space Standard (s.326, Table II) sets the permitted number of persons by floor area: under 4.65 m² (50 sq ft) the room is not counted at all; 4.65-6.50 m² (50-69 sq ft) = 0.5 person; 6.50-8.36 m² (70-89 sq ft) = 1 person; 8.36-10.22 m² (90-109 sq ft) = 1.5 persons; and 10.22 m² (110 sq ft) or more = 2 persons. A child under 10 counts as 0.5 person and a child under 1 is disregarded.

Part M of the Building Regulations covers access and facilities for disabled people. Category 1 (M4(1)) applies to all new dwellings and requires level approach and step-free entrance. Category 2 (M4(2)) is optional and requires wider corridors (1200 mm), 1500 mm turning circles, and step-free access throughout. Category 3 (M4(3)) is wheelchair accessible with even larger room dimensions.