Free London Building Calculators & Checkers

Instant cost calculators and planning checkers built for London homeowners. Get indicative costs, check planning rules, and understand your project before you speak to a builder.

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Eight tools covering the questions London homeowners ask most — from do I need planning permission? to how much will this cost? All free, all client-side, and built to match London's specific rules and costs.

Planning & Compliance
Cost Calculators
Project Management

Why use these tools?

Most homeowners come to a builder's first meeting having searched for cost guides or planning rules, found vague national figures, and left more confused than when they started. These tools are different — they are built specifically for London, where costs are higher, planning rules are tighter, and Article 4 Directions remove permitted development rights in swathes of inner boroughs.

Each tool produces a range, not a single number, because that is what honest estimating looks like. No tool can replace a site visit and a proper quote — but these will help you walk into that first conversation with a realistic frame, the right questions, and a much clearer idea of what you are dealing with.

All tools are entirely free, run in your browser, and store nothing. They are guidance, not a professional determination.

Related guides

The London Extension Guide → Permitted Development Rights → London Construction Cost Guide → The Party Wall Guide →

Ready to get a proper quote?

Our tools give you a starting point. For an accurate, itemised figure — book a free consultation and we will survey your site and send a detailed proposal.

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