How we price: our cost methodology
Every Costwise figure is a from, typical and up-to range built from researched UK guide prices, reviewed and dated, and only changed when the numbers actually move.
Where the numbers come from
We build each price band from current UK supplier and installer pricing, industry cost data and published market figures, then sense-check it against what real jobs of that type actually cost. We show three numbers: a realistic from (a simple job done well), a typical (what most people pay) and an up to (a larger or higher-spec job). They are guide prices, not quotes.
Keeping figures current
Between hands-on reviews we keep prices current by adjusting them for the ONS Construction Output Price Index for housing repair and maintenance, the official measure of what home-improvement work costs to buy, published under the Open Government Licence. That way a figure tracks real construction inflation even in the months between a full review, rather than drifting out of date.
How the calculator works
The calculator ranges your job from the same data: by option for some jobs (for example loft conversion roof type), or per square metre or unit for others (for example a driveway or windows), then applies a regional multiplier. It runs entirely in your browser and sends nothing anywhere.
How regional prices are set
Every guide price is a UK average, and the regional table on each guide, the calculator and the cost map scale it with a fixed multiplier: London 1.20, about 20 per cent above the UK average; the South East and South West 1.05; the Midlands and East 1.00, which is the UK average; and the North, Scotland and Wales 0.97. The cost map applies 12 city factors on the same basis, from Belfast at 0.95 to London at 1.20.
Two things to know before you lean on them. The multipliers were set when the site launched in June 2026 as an estimate of the regional labour spread, not a figure taken from a published construction index. In September 2026 we checked them against the ONS Annual Survey of Hours and Earnings (2025 provisional, region by occupation): median pay for full-time skilled construction and electrical trades employees is about 14 to 17 per cent higher in London than in the Midlands and East, 0 to 7 per cent higher in the South East and South West, and level in the North, Scotland and Wales. Our factors had been 1.30, 1.15 and 0.92. On 3 September 2026 we revised them to the figures above. London and the South carry an allowance above the wage gap for the overheads a quote includes and earnings data cannot see, such as parking, congestion charges, waste disposal, scaffolding licences and travel time; the North, Scotland and Wales factor is a judgement that those overheads run a little below the Midlands, since the wage data shows no gap. The city factors on the cost map follow their region; Northern Ireland is not in the ONS table, so Belfast is a judgement. We publish the working so it can be challenged. And they scale the whole guide price, which is a deliberate simplification: labour is what varies by region, while materials cost much the same everywhere, so the table overstates the regional gap on a job that is mostly materials, such as a new boiler or a stairlift, and understates it on one that is mostly labour, such as painting or hedge cutting. Each guide's regional paragraph says what actually drives the premium for that job. If a multiplier looks wrong for your area, use the route below and we will show the working.
Does the price include VAT
Yes, where VAT is charged at all. Every figure here is what a homeowner pays for the finished job, so where the trader adds VAT it is already in the number. We never publish a figure that has VAT still to come.
What that number is worth to you still moves, because VAT itself moves. A business only has to charge VAT once its taxable turnover passes £90,000 a year, so a sole trader below that threshold charges none, and the same work really is cheaper from a one-van firm than from a national. Some work is zero-rated whoever does it: a stairlift or a home lift supplied for a disabled person, for example. Energy-saving work including solar panels, batteries and heat pumps is at 0% until 31 March 2027, and the figures on those guides already reflect it.
One habit to watch for when you collect quotes. Trades that do commercial work quote the way commercial customers want it, which is before VAT, because a business reclaims it. A survey advertised at £199 plus VAT is £239 to you. That is not a trick, it is a different audience, but it means two quotes can look £40 apart and be identical. Ask whether a price includes VAT before you compare, and compare like with like against the figures here.
Reviewing and dating
We stamp each guide with the month its prices were reviewed and update figures when the market shifts. We do not bump the date cosmetically: if the number has not changed, neither does the date. That dated honesty is the whole point of Costwise.
What these figures are, and what they are not
A Costwise figure is compiled cost data: a researched range for a job, dated, built the way described above. It is not a quote, because nobody has seen your property. It is not a survey or a valuation. On the work itself we are a publisher rather than a trade: Stephen Evans researches, writes and reviews the prices, and is not a gas engineer, electrician, surveyor or builder. Where a job legally requires a registered person, the guide says so and links you to the official register rather than to us. Use these figures to judge whether a quote is reasonable, then hire someone qualified to do the work.
If a figure is wrong
Tell us and we will check it. Email [email protected] with the page and the figure, and the price you were actually quoted if you have one. If it is wrong we change it at source, which moves the guide, its calculator and its cost tables together, because all three read the same number, and the review date on that page changes with it. If it turns out to be right we will say so and show the working rather than leave you without an answer. We would rather be told than be wrong, because accuracy is the only thing this site has.
What we will not do
We do not invent prices, reviews, ratings or statistics, and we do not let installer or affiliate partners influence the figures. We do not publish a percentage where the honest answer is that nobody knows, and we do not claim a qualification we do not hold.