Square Footage Calculator
Calculate the square footage of a rectangle, circle, or triangle area — with results in square feet, square yards, and square meters.
How it works
Area formulas
Rectangle: Area = Length × Width Circle: Area = π × (Diameter / 2)² Triangle: Area = (Base × Height) / 2
Square footage is the area of a surface measured in square feet. For complex floor plans, split the space into rectangles, circles, and triangles, calculate each area separately, then add them together.
Worked example
A 12 ft × 10 ft room is 120 ft². To buy flooring with 10% waste allowance, order about 132 ft². The same room is 13.33 yd² (for carpet, often sold by the square yard) or 11.15 m².
Frequently asked questions
How do I measure square footage of a whole house?
Measure each room (or each rectangular section) separately and add them up. In the U.S., listed square footage typically covers finished, heated living space measured from exterior walls.
How much flooring should I buy for my square footage?
Add 5–10% waste for straight-lay plank or tile and 10–15% for diagonal patterns or rooms with many cuts. Boxes must be rounded up to whole units.
How many square feet are in a square yard?
9 square feet. Divide square feet by 9 to get square yards — useful for carpet, which is often priced per square yard.