By Zencalcy Editorial TeamLast reviewed About us
Square footage is the starting measurement for flooring, paint, rent, HVAC sizing and almost every material takeoff. This calculator measures the common shapes and, for rectangles, lets you add several rooms at once so a whole floor plan can be totalled in one pass.
Area of a room, circle or triangle in square feet and square metres.
Rectangle: A = L × W Circle: A = π × r² Triangle: A = ½ × b × h
Feet-and-inches entries are converted to decimal feet before multiplying (6 in = 0.5 ft). Angles are assumed square; for an L-shaped room, split it into two rectangles and add them.
| Symbol | Meaning |
|---|---|
| L, W | Length and width of a rectangle. |
| r | Radius of a circle, half the diameter. |
| b, h | Base and perpendicular height of a triangle. |
| A | Area, reported in square feet and square metres. |
14.5 × 11.25 = 163.1 square feet, or 15.15 square metres. Adding 10% for cuts gives 179.4 square feet of flooring.
Continue with the Board Foot Calculator, Cubic Yard Calculator, Gallons per Square Foot Calculator, or the Size to Weight Calculator (Rectangular Box) — or browse more construction converters and all construction calculators.
Break it into rectangles and triangles, measure each, and add the areas. A bay window is usually a rectangle plus a half-circle.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026