Irregular Room Square Footage Calculator
Break any complex floor plan into rectangles. Add as many as you need — the calculator sums them into a total.
Last updated:Tip: If you only have the diameter, divide by 2 to get the radius.
L-shape = two rectangles sharing a corner.
Add one row per rectangle and we'll sum them.
How to Calculate Irregular Square Footage
The universal technique is called rectangle decomposition: divide the complex shape into as many rectangles as needed, measure each, and sum the areas.
- Sketch the floor plan on graph paper.
- Draw dividing lines that split the room into rectangles.
- Measure the length and width of each rectangle.
- Enter each rectangle in the tool above and read the total.
Example: Oddly-Shaped Living Room
A living room with a bay window plus an attached alcove:
- Main rectangle: 20 × 15 = 300 sq ft
- Bay window: 8 × 3 = 24 sq ft
- Alcove: 6 × 5 = 30 sq ft
- Total: 354 sq ft
When to Use This Instead of L-Shape
Use the L-Shape calculator when you have exactly two rectangles. Use this tool when you have three or more, or when the rectangles aren't connected to each other.
Frequently Asked Questions
How do I handle curved walls?
Approximate the curve with one or two rectangles. For a bay window, a single rectangle spanning the window width and the deepest point gives a close estimate (usually within 2%).
Is there a limit to how many rectangles I can add?
No practical limit — keep tapping "Add another rectangle" and they all get summed into the total.