Extension Cost Calculator
Plan smarter with instant home extension cost estimates
Get a detailed, region-specific cost breakdown in minutes — no builders, no sales pitch. Just accurate, impartial figures you can adjust to fit your budget and your plans.
1. Tell us about your project
Share a few details about your current home and the extension you’re planning — it only takes a minute.
2. Get a custom estimate instantly
We generate a project plan and cost estimate tailored to your location and your extension requirements including layout, windows, and structural changes.
3. Refine and tailor your estimate
Easily adjust key details to see how they affect costs and make the estimate work for your budget.
automated, accurate estimates
Know what to expect before you build
Getting an accurate estimate upfront means you can start your project with confidence. You’ll understand what your extension is likely to cost before speaking to a builder, helping you avoid surprises, set a realistic budget and make better decisions from day one.
Quick & easy. Just fill out a few details and we’ll break it all down for you.- Tailor your plans to match your budget by adjusting key details anytime
- More than just price per square meter. We base estimates on detailed calculations for greater accuracy.
Take a quick tour
Everything you need to know to get started — in under 3 minutes.
I really appreciated the detailed breakdown of the project cost estimate — it gives a complete total breakdown, including VAT, of everything I could possibly need.
Our guides
Measuring your property
Whether you're planning an extension, loft conversion or renovation, precise measurements form the bedrock of your entire project, affecting everything from planning applications to material quantities and contractor quotes.
Read more
Home extension costs: why price per square metre isn’t enough
Price per square meter is a helpful starting point, but not enough on its own to accurately plan or budget your extension.
Read moreFrequently Asked Questions
