Measurement & Conversion

Square Footage Calculator

This square footage calculator finds the area of rooms and yards of any common shape; our flooring installation guide shows how to use it for ordering. Nearly every construction estimate starts with area. Pick a shape, enter dimensions in feet and inches, and get square feet, square yards, acres and — with the Metric toggle — square meters. For irregular rooms, break the space into simple shapes, calculate each, and add them up.

Results from this square footage calculator are planning estimates; confirm quantities and prices with your supplier or contractor before you order.

Your results will appear here

Enter your measurements and press Calculate. Defaults show a typical example.

How to use the square footage calculator

Pick the shape that matches the space.
Enter dimensions in feet and inches (or switch to metric).
For complex rooms, calculate each part separately and add the results.

Formula

Rectangle = L × W; triangle = ½ × base × height; circle = π × r²; trapezoid = (a + b) ÷ 2 × h. 1 sq yd = 9 sq ft; 1 acre = 43,560 sq ft; 1 sq ft = 0.0929 m².

Worked example

An L-shaped room made of a 12 × 10 ft rectangle and a 6 × 5 ft alcove: 120 + 30 = 150 sq ft (16.7 sq yd).

Tips for using the square footage calculator

Split irregular rooms into rectangles and triangles, then add the areas together.
Measure to the nearest inch and convert inches to decimal feet before multiplying.
Add a waste allowance for the material you are buying after you find the area.
For flooring, paint or roofing, measure the surface you will actually cover, such as wall area for paint or roof area for shingles, not just the floor footprint.