Use our free construction cost calculator London tool to estimate costs for any project in 2025. We cover extensions, loft conversions, stamp duty, bricks and concrete — all London-adjusted, with instant results and no sign-up required.
Our free construction cost calculator London tool helps homeowners and developers plan any building project with confidence. Whether you are pricing a house extension, loft conversion, full refurbishment or new build, our calculators give you an instant estimate based on current 2025 London and UK rates. Furthermore, all tools are updated quarterly against live tender returns and BCIS data.
Each calculator adjusts for your location, build quality and project specification. As a result, you can walk into any contractor conversation knowing your rough budget before a single quote arrives. In addition, our stamp duty calculator covers SDLT, LBTT and LTT — so buyers across England, Scotland and Wales are covered.
Moreover, our brick and concrete calculators help tradespeople and self-builders work out exact material quantities, including wastage allowances. Simply select your calculator below, fill in your project details and get an instant result. No sign-up. No cost. Just honest numbers.
Select your project type using the tabs below. Our house extension cost calculator covers single and double storey rear extensions, side returns and wrap-arounds. The loft conversion cost calculator covers Velux, dormer, hip-to-gable and mansard types. All results include a 10% contingency and exclude VAT and professional fees.
Our free stamp duty calculator 2025 covers SDLT (England and Northern Ireland), LBTT (Scotland) and LTT (Wales). Calculate stamp duty for first-time buyers, home movers, buy-to-let purchases and limited company acquisitions. Rates are updated for 1 April 2025. Enter your purchase price below for an instant banded breakdown.
Our free brick calculator UK works out how many bricks or blocks you need for any wall. Standard half-brick walls use 60 bricks per m². Full brick walls need 120 bricks per m². Concrete blocks use 10 per m². Enter your wall dimensions and openings below — the calculator automatically deducts windows and doors and includes mortar quantities with a 5% wastage allowance.
Our free concrete mix calculator tells you exactly how much cement, sharp sand and 20mm aggregate you need for any pour. Choose your concrete mix ratio — C10, C20, C25 or C30 — and get results in 25kg bags or bulk tonnes. All quantities include a 10% overage allowance. Enter your slab or foundation dimensions below.
Typical cost-per-square-metre ranges for common construction projects. London commands a 15 to 30% premium over UK averages. All figures exclude VAT, architect fees and planning costs.
Single storey rear extension London 2025. Inner London 15 to 25% above outer boroughs. Side return and wrap-around extensions from £2,750/m².
Dormer loft conversion from £45k. Mansard from £70k. L-shaped dormer from £60k. Listed building and conservation area premiums apply.
Minor cosmetic refurb from £600/m². Extensive full-strip refit up to £1,800/m². Average 3-bed full refurb costs £50,000 to £120,000 in London.
New build cost per m² from £2,200 in lower-cost UK regions. Inner London high-spec builds exceed £5,500/m² for bespoke finishes.
Understanding what is and is not covered ensures your project budget is accurate from day one. Furthermore, knowing what to budget separately helps avoid surprises once work starts.
Answers to the most commonly searched questions about UK build costs, stamp duty, bricks, blocks and concrete mixes in 2025.
All results are indicative estimates based on 2025 London and UK rates. Furthermore, every project is different and site-specific factors can affect the final cost. Therefore, always follow up with a written quote from a qualified contractor before committing to a budget.
Our house build cost calculator uses 2025 BCIS-aligned cost-per-m² rates adjusted for your location, quality and project type. It covers rear extension costs, loft conversion costs per m², full house refurbishment and new build cost estimates. Results are typically accurate to plus or minus 15 to 20% and are best used as a feasibility guide before getting written quotes.
Our SDLT calculator is updated for the April 2025 stamp duty changes. The nil-rate band has reverted to £125,000 for standard buyers and £300,000 for first-time buyers. Moreover, we cover all buyer types including first-time buyer stamp duty, home movers, buy-to-let stamp duty, additional properties and limited company purchases in England, Scotland and Wales.
Our brick calculator tells you how many bricks per m² you need. Half-brick walls use 60, full-brick walls use 120, and lightweight blocks use 10 per m². Our concrete calculator works out cement, sand and aggregate for C10 to C30 mixes. In addition, both tools include wastage allowances and can output results in bags or bulk tonnes.
All construction cost calculators on this page are maintained by Signature Build Properties, a London-based design and build contractor with 15+ years of experience across all London boroughs. Rates are reviewed quarterly against BCIS data, Federation of Master Builders surveys and live tender returns. As a result, our figures reflect current market conditions for 2026.
Our extension cost calculator London uses base rates of £2,200 to £3,800/m² with location multipliers for inner London, outer London and UK regions. Our stamp duty calculator reflects the April 2025 changes in full, including the reverted nil-rate bands and the 5% additional dwelling surcharge. Furthermore, our material calculators are based on BS EN 771-1 standard brick dimensions and BS EN 206 concrete mix design ratios.
If you would like a fixed-price quote for your project, our team covers Hayes, Ealing, Hounslow, Richmond upon Thames and Surrey. Contact us for a free site visit with no obligation.
Our design and build team will visit your property, assess the scope and provide a detailed fixed-price quote. No obligation. All London boroughs covered from our Hayes base.
Contact us today to discuss your project and receive a no-obligation quote.
