Who runs The Square Footage Calculator
The Square Footage Calculator is built and maintained by Sri Murugan Systems. We make small, free web tools that do one job well. This site exists so homeowners, contractors and designers can get an accurate area figure for a room, floor, wall, roof or plot without signing up for anything.
How the calculators work
Every calculator uses the standard geometric formula for its shape — length × width for a rectangle, πr² for a circle, (a + b) ÷ 2 × h for a trapezoid, Heron's formula for a triangle from three sides, and so on. Each page states the formula it uses, so you can check the arithmetic yourself. Inputs can be mixed units (feet, inches, yards, meters, centimeters); everything is converted to a common unit before the area is calculated, and results are shown in square feet with conversions to the other units.
How we check accuracy
The worked example on each shape page is calculated from the formula shown on that page, so you can repeat it with a basic calculator and get the same answer. Some combinations of measurements describe a shape that cannot exist — a triangle whose two short sides are shorter than the long side, for instance — and the calculators reject them; see input limits for the full list. Results are estimates for planning and ordering materials; for legal, appraisal or contract purposes, rely on a professional measurement.
Found a mistake?
If a result looks wrong, email contactus@thesquarefootagecalculator.com with the page, the numbers and units you entered, and the answer you expected. Corrections are made to the page itself. More ways to reach us are on the contact page.
Where to start
Use the square footage calculator for a simple rectangular room, browse the guides for flooring, tile, roofing and land, or check the glossary and FAQ for terms and common questions.