The square footage of an L-shaped room is the sum of two rectangles. Split the L into two rectangles, multiply length × width for each, and add them. For example, 15×10 + 8×6 = 150 + 48 = 198 square feet.
Working out a whole floor or parcel? Our flooring square footage guide and house square footage guide build directly on this L-shape method.
How to Calculate the Square Footage of an L-Shaped Room
An L-shaped room is two rectangles joined at a corner, which is why the calculator asks for two lengths and two widths. Open-plan living and dining areas, kitchens with a breakfast nook and many basements are L-shaped, and they are easy to over- or under-measure if the two parts overlap.
The formula
Area = (Length 1 × Width 1) + (Length 2 × Width 2)
Draw an imaginary line from the inside corner to the opposite wall so the floor splits into two rectangles that do not overlap. Measure each rectangle on its own and add the two areas.
How to measure
Pick the split line first, then measure. The most common mistake is measuring the full length of the long wall for both rectangles, which counts the corner square twice. Measure at floor level, wall to wall, and round each measurement to the nearest inch.
Worked example
A living room of 18 ft × 12 ft opens into a dining area of 10 ft × 8 ft.
18 × 12 = 216 sq ft, and 10 × 8 = 80 sq ft.
Total = 216 + 80 = 296 square feet. With a 10% flooring waste allowance, order about 326 square feet.
Where this shape is used
- Flooring and carpet: L-shaped living areas need one continuous order, so the total matters more than either part.
- Kitchens: Countertop-to-wall floor areas around an L-shaped run of cabinets.
- Basements and decks: Finished basements and wraparound decks often step around a corner.
Related shape calculators
Working with a different shape? Try the rectangle calculator, U-shaped kitchen calculator, T-shaped room calculator, or the stepped layout calculator. Each one shows the formula, a worked example and unit conversions.