Permitted Development Calculator
Use this tool as a fast planning triage step before you rely on local council guidance, drawings or formal advice. It is designed to tell you what usually applies, what can change the answer and what to open next.
Run The Quick Check
Permitted Development Calculator
Use this self-check to see whether a common home project still looks comfortably inside the usual permitted development envelope.
Enter the core measurements first, then run the check to see whether the project still looks comfortably inside the usual permitted development range.
Result
The tool keeps the same calculator logic as before and updates this panel after each check.
Choose the project details above, then run the check to see the first-pass result.
What This Tool Is Good For
Best use case
Permitted Development Calculator helps homeowners sense-check the planning route before they commit to drawings, applications or contractor quotes.
What can still change the answer
Exact measurements, local designations, site history and the detailed project design can all shift the final planning route.
Best next step
Use the result to choose the right project guide, local authority page or rule hub rather than treating the tool as the last word.
Questions This Tool Is Best At Narrowing
- Could this project be permitted development?
- Does this proposal still fit the simpler planning route?
- What usually pushes a scheme out of PD?
How This Tool Fits Into The Wider Planning Process
Permitted Development Calculator is intended as a fast planning triage step based on common UK planning considerations and permitted development limits.
Use it to narrow the question, then move into project guides, local authority pages or formal confirmation if the scheme is close to a limit. The tool should help you spend money in the right order, not tempt you to stop checking too early.
Need A More Tailored Steer Than The Tool Result?
If permitted development calculator has narrowed the question but the answer still depends on your exact site, local authority area or project details, use the email guidance route instead of relying on another broad rule of thumb.
Best for
Borderline, location-sensitive or awkwardly specific cases where a broad page is useful, but not quite enough on its own.
What the reply aims to do
Best when a broad guide has narrowed the issue but the live answer still depends on the details of your site, design or local authority area.
What to include
Property type, council area, location, the change you want to make, approximate dimensions, relevant heritage or flat-related details, previous additions and the main concern.
Important: Replies are informational personalised guidance based on the details you provide and publicly available information. They are not formal legal, architectural, surveying or council advice. Site-specific or borderline cases may still need checking with the local authority or a qualified specialist before drawings, applications or contractor spend move ahead.
Your enquiry details are used to respond to your request. Anonymised themes may be used to improve guides, tools, FAQs and site content. Identifiable case details are not published without permission, and sending an enquiry does not sign you up to marketing emails. Privacy notice.
FAQ Pages Worth Opening After The Tool
When A Lawful Development Certificate Is Worth It
Useful when the scheme may be permitted development but you want formal proof before building.
Read answerWhat Counts As The Original House?
Helpful when previous additions may affect how much allowance is left.
Read answerDetailed Guidance Worth Opening Next
Planning Permission
Open the detailed guidance once the tool has narrowed the real planning question.
Open guidePermitted Development
Open the detailed guidance once the tool has narrowed the real planning question.
Open guideDepth Limits
Open the detailed guidance once the tool has narrowed the real planning question.
Open guideHeight Limits
Open the detailed guidance once the tool has narrowed the real planning question.
Open guideBoundary Rules
Open the detailed guidance once the tool has narrowed the real planning question.
Open guideUse These Tools Properly
What they are for
- Reducing uncertainty at the start of the process.
- Helping you pick the right next page quickly.
- Spotting when the answer probably needs escalation before money is committed.
What they do not replace
- Formal confirmation for borderline schemes.
- Local authority checks where special controls apply.
- Country-specific checking where England, Wales or Scotland follow different planning routes.
- Detailed specialist input for complex cases.
When to escalate
- The route only works if the scheme stays inside a tight limit.
- Local controls, listed status or Article 4 may be doing most of the work.
- You need written certainty before drawings, applications or contractor spend.