Our Extension Cost Calculator provides an approximate guide price based on typical London construction rates. Final costs may vary depending on site conditions, bespoke design choices, planning requirements, and finishes. For an accurate quotation tailored to your home, please request a detailed quote.
Extension Cost Calculator
Discover How Much Your Extension Could Cost in Seconds
One of the first things homeowners want to know is: “How much will my extension cost?”
To make things simple, we’ve created our Extension Cost Calculator – a quick and easy tool that gives you an instant estimate in just a few clicks.
Extension costs can vary depending on size, design, and location – especially across London and the surrounding areas. Our calculator takes this into account, giving you a clear idea of what to expect so you can start planning with confidence.
How Our Calculator Works
With our tool, you can:
Choose your extension type – Rear Extensions, Side Return Extensions, Wrap-Around Extensions, Double-Storey Extensions, or Kitchen Extension.
- Adjust size and finishes – from small and functional spaces to large, bespoke designs.
- See estimated costs instantly – based on current London construction prices.
- Visualise your project – with 3D models showing how your extension could look.
It’s designed to be fast, easy to use, and perfect for getting an idea of budget before moving on to detailed quotes.
Why Use Our Extension Cost Calculator?
- Fast & Free – get an instant cost estimate in under 60 seconds.
- Transparent Costs – no hidden extras, just a clear breakdown of key factors.
- Tailored to London Prices – accurate for projects across the whole of London and surrounding areas.
- A reassuring 10-year structural warranty for peace of mind
Serving all of London and surrounding areas, Reltic Extend specialises in premium house extensions designed to add space, style, and value to your home. No matter where you’re based across the capital – from central London to the suburbs – our team is here to bring your vision to life.
Experts in bespoke rear, side, wraparound, kitchen, and double-storey extensions across London.
Our Services
Contact Us
- 4th Floor, Silverstream House, 45 Fitzroy St, London W1T 6EB
- 020 3576 2851
- office@relticextend.co.uk