Scope: Wales. Verified against the Welsh instruments and Welsh Government guidance on 16 August 2026. For England, which has a national numerical minimum that Wales does not, see HMO room sizes in England.
The short answer, because it is the part that surprises people: Wales has no national minimum room size for an HMO. England does. Searching for "the Welsh equivalent of 6.51 m²" returns nothing because there is nothing to return.
What Wales has instead is a set of prescribed amenity standards that apply everywhere, and a council that decides the size question property by property. Both halves matter, and landlords usually know about neither.
What is prescribed nationally in Wales
Section 65 of the Housing Act 2004 says a council cannot be satisfied that an HMO is reasonably suitable for a given number of occupiers if it fails the prescribed standards. In Wales those standards are set by regulation 8 of, and Schedule 3 to, the Licensing and Management of Houses in Multiple Occupation and Other Houses (Miscellaneous Provisions) (Wales) Regulations 2006.
Schedule 3 covers:
- Heating. Each unit of living accommodation must have adequate means of space heating.
- Washing facilities, by ratio. Where facilities are shared: for four or fewer sharing occupiers, at least one bathroom with a fixed bath or shower and a toilet. For five or more, one separate toilet with a wash hand basin for every five sharing occupiers, and at least one bathroom with a fixed bath or shower for every five.
- Hot and cold water to all of it, with bathrooms suitably heated and ventilated, and of adequate size and layout.
- Kitchen facilities where shared: suitably located in relation to the living accommodation, with sinks and hot water, cooking installations, electrical sockets, worktops, storage cupboards, refrigerators with freezer compartments, and extractor and fire safety equipment.
- Within a private unit: a refrigerator, a sink with hot water, worktops, sockets and storage.
Read that list again and note what is not in it. There is no floor area. Where Schedule 3 speaks about size at all it says "adequate size and layout", which is a judgement, not a measurement.
So who decides how big a bedroom has to be?
Your council, in two steps, and it is worth understanding both because they behave differently.
1. Section 65(2) — the standards are a floor, not a ceiling
Section 65(1) means a property failing the prescribed standards cannot be licensed for that number. Section 65(2) then says the authority may decide the house is not reasonably suitable even if it does meet them.
That subsection is the whole game. Meeting Schedule 3 does not entitle you to a licence for the number you applied for. A Welsh council can license a six-bedroom property for four occupiers on suitability grounds, and complying with the national standards is not an answer to it.
2. Section 67 — the conditions that come with the licence
Section 67 lets a council attach conditions about the management, use, occupation, condition and contents of the house — expressly including requirements that facilities and equipment be made available to meet the section 65 standards, that they be kept in repair and working order, and that works be completed within a specified period.
This is where a council's published space standard actually bites: not as a national rule, but as a condition on your licence and as the basis for the maximum occupancy it grants.
The Welsh Government's own position
The Welsh Government's guide for landlords sets out what a council must consider before granting an HMO licence, and the first two items are the suitability of the HMO for the number of occupiers and the suitability of the facilities within it, such as toilets, bathrooms and cooking facilities.
On conditions it is equally plain: the mandatory ones are the gas safety certificate, the safety of electrical appliances and furniture supplied by the landlord, smoke alarms kept in working order with a declaration of their positioning and condition, and a statement of the terms of occupation. Then — and this is the sentence that answers the space question — the council may also specify conditions relating to the facilities in the HMO, its condition and the management of the building.
No room size appears in the Welsh mandatory conditions, because there is not one to appear.
How this differs from England
| Wales | England |
|---|
| Minimum room size |
None nationally. Set by the council through suitability and licence conditions. |
National minimum since 1 October 2018, as a mandatory licence condition. |
| Where it comes from |
Housing Act 2004 ss.65 and 67, plus the council's own published standards. |
Schedule 4 to the Housing Act 2004, paragraph 1A — marked England only. |
| Amenity ratios |
Prescribed nationally in Schedule 3 to the 2006 Wales Regulations. |
Prescribed separately under the England provisions. |
| Waste storage |
A discretionary licence condition, if the council imposes one. |
A mandatory condition — Schedule 4 paragraph 1C, also England only. |
| Mandatory licensing threshold |
Still requires three storeys. |
Storey requirement removed in 2018. |
The last row is the one that catches cross-border landlords, and it is covered properly in the mandatory thresholds article and in the divergence map.
What this means in practice
Do not budget a Welsh conversion off English numbers. The direction of the error is not predictable. A council whose standard is more generous than 6.51 m² costs you a bedroom; one that is content with less does not entitle you to squeeze another in, because section 65(2) sits above whatever the room measures.
The amenity ratios are where small HMOs fail. Five sharing occupiers is the step where a second toilet and a second bathroom arrive. Going from four sharers to five is often presented as one more tenancy; in Schedule 3 terms it can be a bathroom.
The council's published standard is a document, and you can ask for it. It is usually called an HMO amenity standard or an HMO licensing standard, and it will contain the room sizes, the ratios the council applies above the national minimum, and its kitchen and fire requirements.
What to check with your own council, in order
- Ask for the published HMO amenity and space standard. Not the licence application form — the standards document behind it.
- Ask what maximum occupancy it would grant for the property as it is. This is the section 65 question, and the answer decides your rent roll.
- Ask whether additional licensing applies at your address as well as mandatory — see HMO licensing in Wales.
- Get the answer in writing, dated, and keep it with the property. A standard can change between your conversion and your application. See record keeping.
- Remember Rent Smart Wales is separate and applies regardless — registration versus licensing.
We publish the licensing position for every Welsh council we can evidence, with the date each was checked, at the council index. What we do not hold is a national table of Welsh council space standards — each is a separate document published by each council, and we would rather send you to yours than average twenty-two of them into a number that is true nowhere.
Try the tool. The HMO room size checker asks which country the property is in before anything else, and for Wales it returns this position rather than an English number. It is the fastest way to show a builder, a lender or a co-investor that the 6.51 figure they have quoted at you is the wrong jurisdiction.
Run the free compliance check for the duties that apply to your property, and see the management regulations for the duties that bind an HMO whether or not it is licensed.