Red Line Boundary Tool

Draw a red-line boundary around your site on an Ordnance Survey map, check the enclosed area, and make sure it includes everything a planning application needs before you order a formal plan.

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Your red line

Search for your property, then use Draw red-line boundary to click each corner of the site. The enclosed area updates as you draw.

What your red line must include

The whole planning unit — the full extent of the property the application relates to.
All land needed for the proposal, including gardens and parking affected by the works.
Any access — driveways, shared lanes or the point where the site meets the public highway.

Common reasons councils reject a red line

The access route is left outside the boundary.
The line is drawn too tightly around the building only.
It is hand-sketched rather than drawn on an accurate OS base map.

Get a compliant red-line location plan

Order an official 1:1250 OS site location plan with the red-line boundary, scale bar and north point — ready to upload to the planning portal.

From £7.95

Create a site location plan

What is a red line boundary?

A red-line boundary is the edge drawn in red around the site a planning application relates to. It tells the council exactly which land is included, and it must usually cover the whole planning unit plus any access to the public highway. A separate blue line is sometimes used for other land in the same ownership nearby.

This tool lets you sketch that red line on an accurate OS map and instantly see the enclosed area, so you can sense-check the extent before buying a plan. When you are ready to submit, you will need a formal site location plan at a recognised scale.

For more detail, read the red-line boundary rule explained and our guide to red-line boundaries for extensions.