How many homes can I build on my land? A first look before you buy

Why there's no "homes per acre" answer

The question "how many homes can I build on my land?" often comes with a hope that there's a ratio: so many homes per acre or per hectare. In England, there isn't one that applies everywhere.

National policy asks for efficient use of land, judged site by site. The National Planning Policy Framework (NPPF, August 2026), policy L3, says proposals "should make efficient use of land", taking account of housing need, local market conditions, infrastructure, connectivity and "the importance of securing well-designed, attractive and healthy places". Within settlements, residential schemes "should contribute to an increase in the density of the area in which they are situated", unless there's a clear justification. Proposals that don't make efficient use of land "should be refused".

The one national number is a minimum near stations. Under NPPF policy L3(2)(c), schemes within reasonable walking distance of a well-connected station should achieve at least 35 dwellings per hectare within the net developable area, and at least 45 dwellings per hectare where the service is at least twice as frequent as the minimum. The NPPF glossary sets out what counts:

• Reasonable walking distance: about 800 metres, or about 10 minutes' walk.
• Well-connected station: a station or stop in one of the larger travel-to-work areas, with a set minimum daytime service (the glossary gives the details).
• Net developable area: the part of the site for housing and directly associated uses, including access roads, private gardens and ground-level parking, but excluding things like strategic infrastructure, parks and significant biodiversity or drainage features.

These are minimums, not targets, and the NPPF says they "should be exceeded where possible". They don't tell you what a particular site can take.

Your local plan matters as much. Councils set their own policies on density, character, height, space standards, accessibility and affordable housing. Read the adopted local plan and any design code for the area before you form a view.

In London, the London Plan 2021 has no density matrix. Policy D3 says all development "must make the best use of land by following a design-led approach that optimises the capacity of sites". A new London Plan was out for consultation until 15 October 2026 and isn't adopted yet.

Step 1: Find the land you can actually build on

The red line on a sales plan is not the area you can build on. Start by taking away what you can't build over, or shouldn't:

• Access. A safe way in for vehicles, refuse and emergency services, and the land the road takes.
• Trees. Protected trees and their root protection areas.
• Easements and services. Sewers, water mains and cables, often with strips you can't build on.
• Neighbours. Privacy and outlook distances, and the daylight and sunlight their windows rely on.
• Flood risk, heritage and ecology. A conservation area, listed buildings nearby, habitats or flood zones can shape or shrink the developable area.
• Rights and title. Rights of way, restrictive covenants and boundary questions are legal matters. Ask your solicitor.

What's left is roughly your net developable area. On a small site, the access road and the distances to neighbours often take more land than people expect.

Biodiversity net gain is worth checking at this stage too. From 6 August 2026, the mandatory requirement doesn't apply to new planning applications for sites of 0.2 hectares or less, unless the scheme affects on-site priority habitat (gov.uk, Biodiversity net gain: exempt developments). Larger sites need to plan for it.

Step 2: Test a building envelope

Next, work out roughly how big a building the site could take: its footprint, its height and its shape. This is where planning judgement comes in. The envelope is shaped by:

• Context and neighbours. The height and grain of the street, the building line, and overlooking and overshadowing of existing homes.
• Policy. Local height policies, conservation area appraisals, design codes and any planning history on the site or its neighbours. A refusal on the site, or an approval next door, tells you a lot.
• Outdoor space. Gardens, balconies and communal space take room on the plan. In London, the London Plan 2021 (policy D6) sets a minimum of 5 m² of private outdoor space for a one- or two-person home, plus 1 m² for each extra occupant, with a minimum depth and width of 1.5 m.

We test several envelopes, not one: a lower, wider option and a taller, narrower one can give similar numbers with very different planning risk.

Step 3: From floor area to homes

Once you have a building envelope, you can estimate how many homes fit inside it.

Start from gross internal area (GIA), then take off what isn't a home. Stairs, lifts, corridors, bin and bike stores, plant and wall thicknesses all take floor area. The ratio of saleable or lettable home area to total floor area is often called net-to-gross, and it varies a lot with the building type. A row of houses has almost no shared circulation; a block of flats with a lift and a corridor has much more.

Then divide by real home sizes. The nationally described space standard (NDSS, DCLG 2015) sets minimum gross internal floor areas. A few common sizes from its Table 1:

The NDSS also sets minimum bedroom sizes (a single bedroom at least 7.5 m², a double at least 11.5 m²), built-in storage and a minimum ceiling height of 2.3 m for at least 75% of the GIA. In London, policy D6 of the London Plan 2021 asks for 2.5 m.

The NDSS is not a building regulation. It applies where your local plan adopts it, which many do, and the NPPF (policy PM13) lets councils set internal space standards only to implement it. Check your local plan. Even where it isn't adopted, homes below these sizes are harder to get through planning and harder to sell or let, so we use it as the floor for every first look.

A worked example (arithmetic only). Suppose one floor of a block of flats gives 300 m² of GIA for homes after the stair, lift and corridor. On paper, that's four two-bedroom, four-person flats at 70 m² each (280 m²), or six one-bedroom, two-person flats at 50 m² each (300 m²). Real layouts rarely divide that neatly: windows, structure, the stair position and dual aspect all change the answer. That's why we lay homes out on a plan rather than divide areas.

Mix matters as much as the count. Six one-bedroom flats and four two-bedroom flats are different schemes, and the council's housing need evidence and affordable housing policy shape which mix is acceptable.

Step 4: Check the thresholds that change the scheme

Some numbers change what you're building, not just how much. It's worth knowing where they sit before you settle on a figure.

10 homes, or 0.5 hectares. The NPPF glossary defines major development, for housing, as 10 or more homes or a site of 0.5 hectares or more. Major schemes usually bring affordable housing requirements, more application documents and, under NPPF policy DM1, an expectation of early engagement, including pre-application engagement.

Accessible and adaptable homes. Approved Document M Volume 1 sets three categories: M4(1) visitable, M4(2) accessible and adaptable, and M4(3) wheelchair user. Categories 2 and 3 apply only where a planning condition requires them. The NPPF (policy HO5) asks development plans to make sure no less than 40% of homes on major developments meet M4(2). In London, policy D7 of the London Plan 2021 asks for at least 10% M4(3) and the rest M4(2). The NDSS notes that its sizes aren't enough for wheelchair homes, so M4(3) homes take more space.

Height, stairs and fire. For blocks of flats, Approved Document B Volume 1 (with the amendments that took effect on 30 September 2026) sets lines that change the core of the building:

• A "small single stair building" is limited to a top storey no more than 11 m above ground and no more than three storeys above the ground storey.
• Blocks of flats with a top storey more than 11 m above ground need sprinklers throughout (paragraph 7.4).
• Where the top storey is 18 m or more above ground, flats should be served by more than one common stair (paragraph 3.30). A second stair takes floor area on every level.

Higher-risk buildings. Under section 65 of the Building Safety Act 2022, a building at least 18 m high or with at least seven storeys, containing at least two homes, is a higher-risk building. The Building Safety Regulator is the building control authority for these. Relevant buildings also need a fire statement with the planning application (Town and Country Planning (Development Management Procedure) (England) Order 2015, article 9A).

So nine homes and ten, or a top storey just under and just over 18 m, can be very different projects. A first look should say which side of each line you're on.

So, how many homes can I build on my land? Put a range on it

A useful first answer is a range with reasons: "between X and Y homes, depending on height and mix; the main planning risks are A and B". A single number with no reasoning invites false confidence.

For each option, we'd want to see:

• The site plan, with constraints and the net developable area.
• The building envelope, in plan and 3D.
• A unit mix and area schedule, checked against the NDSS.
• Where the scheme sits against density, accessibility and fire thresholds.
• The planning risks, issue by issue, and what would reduce them.

Common mistakes we see: treating a neighbour's approval as a promise; dividing the gross site area by a homes-per-hectare figure; forgetting the stairs, lifts and stores; and ignoring the thresholds above.

What a first look can't tell you

A first look is a test, not a permission. It can't tell you what the council will decide; only a planning application does that. Pre-application advice can help, but it doesn't bind the council's decision (Planning Practice Guidance, Before submitting an application). It also isn't a valuation, a survey, a legal check of title or a daylight report. We cover what a feasibility study does and doesn't include in What a feasibility study tells you, and what it doesn't.

How we test capacity in a Feasibility Sprint

In a Feasibility Sprint, our architects visit the site, review planning policy and the site's history, map the constraints and test three massing options. Each option comes with a unit mix and area schedule checked against the NDSS, and the planning risks rated issue by issue. You get a report, a 3D model and a review call. The fee is fixed and quoted per site after a free intro call.

Frequently asked questions

Looking at a specific site?

If you're weighing up a site, the Feasibility Sprint tests what it can hold and how the options compare, before you commit. It covers sites in England.

Book a free intro call or see the Feasibility Sprint.