Measure an L-shaped room by splitting it into rectangles
The rectangle calculator can support an irregular room calculation if you divide the plan into nonoverlapping rectangular pieces.
Rectangle area →Choose one clear decomposition
Imagine an outer rectangle 6 m by 4 m with a 2 m by 1.5 m rectangular corner removed. The outer area is 24 m² and the removed area is 3 m², leaving 21 m². Calculate each rectangle separately and subtract. Alternatively split the actual L shape into two nonoverlapping rectangles and add their areas; both methods should agree.
Prevent double counting
Label every piece on a sketch and ensure the pieces cover the floor exactly once. Overlapping rectangles inflate the answer, while overlooked recesses reduce it. Use inside dimensions when calculating usable internal floor area, and distinguish structural wall thickness from the space being covered. If a boundary is sloped or curved, a rectangular decomposition alone may only approximate it.
Do not add the piece perimeters
Adding areas is valid for disjoint pieces, but summing their perimeters counts internal dividing lines twice. For edging, trace only the exterior boundary and add the actual edge lengths. For material purchasing, apply the relevant cutting allowance after calculating the net area, then round for pack sizes. Keep both the geometric area and the purchasing quantity recorded so later changes can be checked independently.
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