Square Footage Calculator
0 square feet
How Square Footage Is Calculated
Square footage is simply the area of a surface expressed in square feet. For a rectangle (the most common case for rooms, lots, and flooring), area equals length times width. For a circle — a round patio or rug, for example — area follows the standard geometric formula A = πr², where r is the radius. For a triangle, area is one-half times base times height (A = ½ × b × h). Whatever unit you enter your measurements in, this calculator first converts the dimensions to feet, then applies the appropriate formula so the result is always in true square feet.
Why Unit Conversion Trips People Up
A common mistake is mixing units — entering length in feet and width in inches — which throws the result off by a factor of 12 or more. Because every input field here shares one unit selector, all dimensions are converted consistently before the area is computed, avoiding that error. If you're working from architectural drawings or a survey in meters or yards, switch the unit selector rather than manually converting each number yourself.
Turning Area Into a Project Estimate
Once you know the square footage, you can estimate material needs or costs — enter a price per square foot above to see a rough budget for flooring, turf, or paint coverage. For material-specific quantity estimates, see the tile calculator or the mulch calculator.
Frequently Asked Questions
How do I calculate square footage of a room that isn't a perfect rectangle?
Split the room into rectangles, circles, or triangles, calculate each section's area separately using this calculator, then add the results together. For an L-shaped room, for example, treat it as two rectangles and sum their square footage.
How do I convert square meters or square yards to square footage?
Enter your length and width (or radius, or base/height) using the unit selector set to meters or yards, and the calculator converts the dimensions to feet internally before computing the area, then also displays the result back in square yards and square meters for cross-checking.