UK building cost calculator
Estimate building work costs before you ask for quotes.
Get a realistic early Guide Price for an extension, loft conversion, renovation, kitchen, bathroom, basement or refurbishment. Proper Job shows the assumptions and cost drivers behind the range so you can plan the next conversation.
What can you estimate?
Proper Job is designed for common UK residential building work, including house extensions, loft conversions, kitchen and bathroom renovations, whole-property refurbishments, basement conversions, lower-ground floor work, flooring, plastering and painting and decorating.
How the calculator works
- Choose the type of building work and enter the area affected.
- Add the location, finish, access, structural and associated-work details that are known.
- Review the early price range, assumptions, exclusions and decisions still to confirm.
- Move to an itemised Detailed Estimate when your architectural drawings and decisions are ready.
Why there is no single UK building price per square metre
Two projects with the same floor area can have very different costs. Structure, drainage, access, glazing, kitchens, bathrooms, services, preparation, finish level and work to the existing house can all change the scope. A useful calculator exposes those drivers instead of presenting a false single national rate.
Questions homeowners ask
What does a building cost calculator calculate?
Proper Job creates an early Guide Price range using the project type, size, postcode area, finish level, site conditions and likely associated work. It is a planning range, not a fixed quotation.
Can I calculate the cost of a house extension?
Yes. Start with the extension type and new floor area, then add relevant kitchen, bathroom, structural, glazing, access and site details. A house extension cost depends on more than its area alone.
Can I calculate a loft conversion or renovation?
Yes. Proper Job supports loft conversions, refurbishments, kitchen and bathroom renovations, basement work, lower-ground work and other common building projects.
When do I need a Detailed Estimate?
Use a Detailed Estimate once the main decisions and architectural drawings are ready. It measures supported drawing information and organises it into itemised work packages for review.
Is a Proper Job Guide Price a quote?
No. It is an early budget range to help you plan and compare scope. A builder still needs to check the property, drawings, specification, exclusions and current site conditions before giving a firm quote.