Guides · Floor Plan Measurement

How to Measure an L-Shaped Floor Plan

L-shaped homes are among the most common non-rectangular floor plan shapes. They look more complex than they are. You can measure an L-shape as a single polygon or as two overlapping rectangles — both methods work and give the same result. Here's both approaches.

Approach 1: Trace the full L as one polygon (recommended)

The measurement tool supports any polygon shape including concave shapes like an L. Start at any exterior corner. Click clockwise (or counterclockwise, consistently) around the outside of the L placing a point at each corner. A basic L-shape has 6 corners. Double-click at the last point (or click the first point) to close the polygon. The tool calculates the full L area directly. This is fastest and most accurate — no math required, just trace what you see.

Approach 2: Two rectangles

An L-shape can be divided into two non-overlapping rectangles. Draw two separate rectangular polygons covering the full L without double-counting. Make sure they share exactly one edge at the inner corner of the L and together cover the complete footprint. Add both polygon areas for total GLA. This approach is useful if you want to verify by checking the math or if the floor plan image makes two simple rectangles easier to trace than the full L outline.

Example walkthrough

Home is 40 feet wide × 60 feet long with a 20 × 20 foot cutout at the rear-left corner. Full rectangle = 40 × 60 = 2,400 sq ft. Cutout = 20 × 20 = 400 sq ft. L-shaped area = 2,000 sq ft. Using the full-L polygon approach: trace all 6 corners of the L, tool returns approximately 2,000 sq ft. Using two-rectangle approach: 40 × 40 = 1,600 sq ft + 20 × 20 = 400 sq ft = 2,000 sq ft. Same result, confirmed by both methods.

L-shaped homes with garage in the L corner

Many L-shaped homes have the garage filling the inner corner. In this case trace the living space perimeter only, excluding the garage area. The result is a rectangle with the garage area removed — trace all corners including the garage recess corners, but with the garage itself outside the polygon.

More complex shapes

T-shapes, U-shapes, and other multi-directional footprints follow the same logic. Trace the outer perimeter as a single polygon, placing a point at every exterior corner. The tool handles any number of corners and any shape, whether convex or concave.