Free Online Calculators
A garage conversion in the UK typically costs between £6,000 and £30,000, depending on the size, type of conversion, and finish quality. The average cost for a standard single garage conversion sits around £10,000–£15,000. Use the breakdown below to estimate your specific project cost.
A garage conversion cost calculator helps homeowners estimate how much they will spend turning an unused garage into a liveable space whether that is a bedroom, home office, gym, annexe, or kitchen extension.
Rather than guessing, you can use cost-per-square-metre figures, regional pricing data, and project-specific variables to get a realistic budget before speaking to a builder.
This guide works as your complete calculator and cost reference. It breaks down every cost factor so you can build your own accurate estimate from scratch.
Current market data from 2026 shows clear price bands that help you budget with confidence:
| Garage Type | Size (m²) | Average Cost | Cost Per m² | Cost Per Sq Ft (approx.) |
|---|---|---|---|---|
| Single Integral | 15–16 | £10,000–£15,000 | £625–£950 | £58–£88 |
| Single Attached | 15–16 | £12,000–£18,000 | £800–£1,125 | £74–£105 |
| Single Detached | 15–16 | £14,000–£20,000 | £875–£1,250 | £81–£116 |
| Double Integral | 25–30 | £16,000–£25,000 | £650–£950 | £60–£88 |
| Double Detached | 25–30 | £20,000–£32,000 | £800–£1,200 | £74–£111 |
These figures include labour, materials, insulation, electrics, heating, flooring, and basic decoration. Premium finishes with underfloor heating, bifold doors, or en-suite bathrooms push the upper end higher. In our experience helping UK homeowners, most projects land comfortably in the middle range when you plan carefully.
If you want a straightforward cost-per-square-metre estimate, here is what you should expect in 2025:
So if your garage is 18 m² and you want a mid-range finish, your estimated cost would be:
This garage conversion cost per m² calculator method gives you a reliable ballpark before you get quotes from local tradespeople.
Follow these steps to build your own garage conversion cost estimate:
Measure the internal length and width in metres and multiply them together. A typical single UK garage is around 4.8 m × 2.4 m = 11.5 m² to 5.5 m × 3.0 m = 16.5 m².
Decide what the space will become. A simple home office costs far less than a bathroom or annexe because plumbing, electrical upgrades, and compliance requirements add significant cost.
Multiply your floor area by the appropriate rate for your specification level (basic, mid-range, or high-spec).
Some costs remain roughly fixed regardless of size. These include:
Labour costs vary significantly across the UK. Prices in London and the South East can be 20–40% higher than the Midlands or North of England. If you are based in London, multiply your estimate by 1.25–1.40.
Always add 10–15% of your total budget as a contingency for unexpected structural issues, damp problems, or design changes.
Understanding where your money goes helps you make smarter decisions and spot overpriced quotes. Here is an honest, experience-based breakdown:
This is non-negotiable for any liveable space. Garages are not built to residential thermal standards, so you will need insulation in the floor, walls, and ceiling/roof.
The concrete garage floor usually needs levelling and a damp-proof membrane before any finish goes down.
Once walls are dry-lined, they need skimming for a smooth finish.
A new consumer unit spur or full rewire of the space, plus sockets, lighting, and potentially an EV charger if converting a garage attached to the home.
Most garages have a large metal or wooden door that needs replacing with a window and wall infill, or a glazed partition.
You need to extend the home's central heating or install a standalone solution.
If you are replacing the garage door opening with a solid wall or glazed section, this is one of the most visible and structural elements.
Several variables push your final cost up or down. Being aware of them helps you control your budget.
An integral garage shares at least one wall with the house, which makes connecting to the home's heating, electrics, and plumbing much easier and cheaper. A detached garage requires separate utility connections and often full planning permission, which adds cost.
A well-maintained, dry garage with a solid roof and level floor costs less to convert. A garage with damp penetration, roof damage, or a cracked floor requires remedial work before the conversion can begin. Always have a builder inspect the structure before accepting any quote.
Converting to a bedroom or office is relatively straightforward. Converting to a bathroom, kitchen, or self-contained annexe involves significantly more trades plumbers, gas engineers, electricians all of which push the cost up.
There is a huge difference between a basic conversion with standard fittings and a high-spec conversion with underfloor heating, skylights, bespoke storage, and premium surfaces. Be honest with yourself about what level of finish you need.
Labour rates vary enormously. A mid-range single garage conversion that costs £12,000 in Manchester might cost £16,000–£18,000 in London. Always get at least three local quotes.
If your garage shares a wall with a neighbour, you may need a party wall agreement before work starts. This adds legal fees of £700–£2,000 but is a legal requirement under the Party Wall Act 1996.
In most cases, converting an integral garage into a living space falls under permitted development rights in England, meaning you do not need full planning permission. However, you will almost always need building regulations approval, which is a separate process.
You will likely need planning permission if:
Always check with your local planning authority before work starts. Getting this wrong can cost you significantly more in retrospective applications or enforcement action.
Building regulations approval is required for virtually all garage conversions. It ensures the work meets standards for insulation, structural integrity, fire safety, ventilation, and electrical safety. The fee for a building regulations application ranges from £200 to £500 depending on the local authority.
An ADU accessory dwelling unit is a fully self-contained living space with its own kitchen, bathroom, and entrance. In the UK this is often called an annexe or granny flat.
Converting a garage into an ADU is one of the more complex and expensive garage conversion types. You should budget:
The higher cost reflects the need for a full kitchen installation, bathroom with all plumbing, separate electrical meter (sometimes), compliance with habitation standards, planning permission (almost always required), and separate access.
If you plan to rent the ADU out as a separate tenancy, you will also need to ensure the property meets landlord licensing requirements and fire safety regulations in your local authority area.
London and South East:
£900–£1,500 per m²
East of England:
£700–£1,100 per m²
South West:
£650–£1,000 per m²
East Midlands:
£600–£950 per m²
West Midlands:
£600–£950 per m²
Yorkshire and Humber:
£550–£900 per m²
North West:
£550–£900 per m²
North East:
£500–£850 per m²
Scotland:
£550–£900 per m²
Wales:
£500–£850 per m²
Northern Ireland:
£450–£800 per m²
These figures are based on 2025 market data and reflect mid-range specification conversions including materials and labour.
From an investment standpoint, a well-executed garage conversion typically adds 10–20% to a property's value in the UK. On a £350,000 home, that could mean £35,000–£70,000 in added value.
Even at a mid-range project cost of £15,000, the return on investment is strong — especially compared to building a new extension, which typically costs £30,000–£60,000 for a similar floor area.
Beyond financial value, a garage conversion gives you usable living space without reducing your garden size, disrupting neighbours significantly, or waiting through a lengthy planning process in most cases.
The best value conversions tend to be bedroom additions in family homes, home offices in suburban properties, and annexes in areas with high rental demand.
Getting accurate quotes from tradespeople takes a little preparation. Here is what experienced homeowners recommend: