Most of the kitchen dimensions UK designers actually work to are industry convention, not law. There is no minimum kitchen size in the building regulations at all: no floor area, no minimum run of units, nothing a building control officer can measure and reject on size alone. What the regulations fix, where the accessible standards apply, is the clear space that has to survive between the units once they are installed, and how much air the room has to move. Those two things decide almost every kitchen layout in a London house, and they are the numbers most refits get wrong.
This guide sets out what is actually required, what is merely conventional, and where the line between them falls. It is the kitchen companion to our note on minimum bathroom size, which works the same way.
What the regulations actually require
Three Approved Documents matter, and only one of them is about size.
Part M sets the clear space around units, but only under the higher optional standards. M4(1), the visitable dwellings standard, is the default for newly erected dwellings and says nothing about kitchen layout. M4(2), accessible and adaptable dwellings, and M4(3), wheelchair user dwellings, apply only where a planning condition imposes them. If your project is a private refit in an existing house, none of this is mandatory, which is exactly why it is worth reading: the numbers were derived from how people actually move around a kitchen.
Part F sets ventilation, and it applies to everyone. This is the requirement most commonly missed in a kitchen refurbishment.
Part J applies where a combustion appliance is installed, and Approved Document F notes this explicitly for kitchen work.
The clearances that decide everything
Under M4(2), a minimum 1200mm clear space is provided in front of and between all kitchen units and appliances. That is the whole requirement, and it is measured to the face of the units, so a galley with 600mm runs on both sides needs a room 2400mm wide before you have satisfied it.
Under M4(3), there is a minimum clear access zone 1500mm wide in front of, and between, all kitchen units and appliances, and the kitchen and principal eating area must be in the same room or connected, on the entrance storey. That takes the same galley to 2700mm.
Neither figure applies to an ordinary refit. Both are good design targets anyway. Below about 1000mm between opposing runs, two people cannot pass, an oven door and a dishwasher door cannot both be open, and the room stops working the moment a second person walks in.
Floor area, where it is set at all
Neither standard fixes a kitchen size on its own. M4(3), at paragraph 3.31, does fix a minimum combined internal floor area for living, dining and kitchen space taken together.
| Bedspaces | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|
| Minimum combined area (m2) | 25 | 27 | 29 | 31 | 33 | 35 | 37 |
This is one number for the whole social heart of the dwelling, which is why open-plan layouts satisfy it more easily than a separate galley kitchen plus a separate sitting room. It is also why an open-plan knock-through is so often the answer in a London terrace, though that brings structural questions of its own: see our guide to removing a load-bearing wall.
Worktop lengths, where M4(3) applies
M4(3) is the only place the regulations specify how much kitchen you need. For a wheelchair adaptable dwelling, the minimum overall worktop length, including fittings and appliances and measured through the mid-line of the worktop rather than the front or rear edge, is 4330mm for two bedspaces, 4730mm for three or four, 5630mm for five and 6730mm for six to eight.
For a wheelchair accessible dwelling the figures rise to 6130, 6530, 7430 and 8530mm respectively, and a series of further requirements attach:
- A continuous section of worktop at least 2200mm long incorporating a combined sink and drainer unit and a hob, height adjustable or capable of being refixed at alternate heights, with no fixed white goods beneath it and clear open leg space of at least 700mm above floor level.
- A sink no more than 150mm deep, insulated underneath to prevent scalding.
- Lever operated taps.
- Space for a built-in oven with its centre line between 800mm and 900mm above floor level, and a pull-out shelf beneath the oven enclosure.
- At least 400mm of worktop to one side of the oven, and to one side of a tall fridge or fridge freezer.
- Drainage either flexible or easily adaptable to worktop heights between 700mm and 950mm above finished floor level.
Even on a project where none of this is required, the 400mm landing space beside an oven and a tall fridge is the detail worth stealing. It is the single most common omission in a fitted kitchen, and you notice it every time you take something hot out of the oven.
Ventilation: the requirement everyone misses
Part F applies to every kitchen, not only accessible ones, and the numbers are specific.
For an intermittent extract system, the minimum rate is 30 litres per second where a cooker hood extracts to the outside, and 60 litres per second where there is no cooker hood or the hood does not extract to the outside. For a continuous system, the kitchen high rate is 13 litres per second.
Approved Document F is blunt about the fashionable option: a recirculating cooker hood on its own does not provide a means of ventilation that complies with Part F. If your island hob has a recirculating extractor and nothing else, the kitchen does not comply, however good the filters are. That is worth knowing before the worktop is templated.
Two further dimensions come from the same document. Where a cooker hood extracts outside, its height above the hob should follow the manufacturer's instructions or, where none exist, sit between 650mm and 750mm, and the hood should span at least the full width of the cooker. Extract terminals and fans other than cooker hoods should be as high as practicable in the room and a maximum of 400mm below the ceiling.
On refurbishment specifically, existing fans and outside-extracting cooker hoods should be retained or replaced and checked that they still work. If there was no ventilation system in the original room, you do not have to create one. And if an extractor fan or cooker hood is replaced using the existing cabling, that does not need to be notified to a building control body.
Note the timing: a 2026 edition of Approved Document F Volume 1 has been published and takes effect on 24 March 2027 in England for work not connected with higher-risk building work, and 24 September 2027 for work that is. The kitchen extract rates are unchanged between the current edition and the 2026 one, so the figures above hold either side of that date.
The dimensions that are convention, not law
Most of the numbers a kitchen fitter will quote you are British industry standards rather than regulations. They are still the right defaults, because every appliance and every carcase is made to them.
- Worktop height 900mm. Built up from a 720mm carcase, a 150mm plinth and a 30 to 40mm worktop. Adjustable feet let you vary this, and moving a run 20 to 30mm to suit the person who actually cooks is a legitimate bespoke decision.
- Base unit depth 600mm, with a worktop typically 600 to 650mm to give a small overhang.
- Wall unit depth 300 to 350mm, hung to leave roughly 450 to 600mm between worktop and the underside of the wall units. Less and you cannot use the worktop; more and the top shelf is out of reach.
- Island walkways of 1000 to 1200mm. The lower figure works for one cook, the upper for a family kitchen where people pass behind each other.
- Landing space either side of the hob and sink, ideally 300mm minimum, 400mm where you can find it.
None of these are enforceable. All of them are what makes the difference between a kitchen that photographs well and one that works at seven o'clock on a Tuesday.
How to use this on a real project
Establish first which standards your project is actually subject to, because the answer changes the whole exercise. A private refit in an existing house answers to Part F and, if you are moving gas, Part J. A new dwelling answers to M4(1) as a minimum. Only a planning condition brings M4(2) or M4(3) into play, and if it does, the 1200mm or 1500mm clear zone is the constraint the layout has to be built around rather than fitted into afterwards. For flats there is a further layer: see our notes on the licence to alter and on building regulations for a London renovation.
Then design to the clearances even where they are voluntary. A 1200mm gap between opposing runs, 400mm of landing space beside the oven and a hood that genuinely extracts outside will do more for how the room feels than any finish decision. Our guide to designing an open-plan kitchen diner takes the layout question further, and the cost guide covers what the work runs to.
Frequently Asked Questions
Is there a legal minimum kitchen size in the UK?
No. The building regulations set no minimum floor area for a kitchen. Where the higher accessibility standards apply, Approved Document M sets a minimum combined floor area for living, dining and kitchen space together, from 25 square metres for two bedspaces up to 37 for eight, and it fixes clear access zones around the units. Those clearances, not a room size, are what a layout has to satisfy.
How much space do you need between kitchen units?
Where M4(2) applies, a minimum 1200mm clear space in front of and between all kitchen units and appliances. Where M4(3) applies, that rises to a 1500mm clear access zone. Neither is a general requirement for every kitchen: M4(1) is the default standard for new dwellings and the higher standards apply only where a planning condition imposes them. As a working number for a comfortable galley, 1200mm is the figure to design to whether or not it is compulsory.
What is the standard kitchen worktop height and depth?
900mm high and 600mm deep is the British standard arrangement, built up from a 720mm carcase, a 150mm plinth and a worktop of around 30 to 40mm. It is an industry convention rather than a building regulation, so it can be varied, and raising or lowering a run by 20 to 30mm to suit the people who cook is one of the few genuinely bespoke decisions in a kitchen.
What extract rate does a kitchen need?
For an intermittent system, 30 litres per second where a cooker hood extracts to the outside, or 60 litres per second where there is no hood or the hood does not extract outside. For a continuous system, a high rate of 13 litres per second. A recirculating cooker hood on its own does not satisfy Part F, which is the single most common failure in a London kitchen refit.
How high should a cooker hood be above the hob?
Follow the manufacturer's instructions. Where none are available, Approved Document F says between 650mm and 750mm above the hob surface, and the hood should span at least the full width of the cooker. Extract terminals and fans other than cooker hoods should be as high as practicable in the room and no more than 400mm below the ceiling.
Do I need building control approval to replace a kitchen extractor?
Not always. Approved Document F states that if an extractor fan or cooker hood is replaced using the existing cabling, it does not need to be notified to a building control body. Where you are carrying out building work in a kitchen, existing fans and outside-extracting cooker hoods should be retained or replaced, and checked to confirm they still work.
Sources
- Approved Document M Volume 1, access to and use of dwellings, paragraphs 2.24 and 3.31 to 3.34, Tables 3.2, 3.3 and 3.4: gov.uk
- Approved Document F Volume 1, ventilation, paragraphs 1.16 to 1.18, Tables 1.1 and 1.2, Diagrams 1.1 and 1.2, and paragraphs 3.30 to 3.32: gov.uk
Checked on 2 September 2026. Approved Document M4(2) and M4(3) apply only where a planning condition imposes them. Worktop heights and unit depths are industry conventions, not regulations. Confirm which standards your project is subject to with your building control body before you finalise a layout. More guides at the Vertigo Interiors homepage.