Square Footage Calculator
Measure rectangular, square, circular, triangular or trapezoidal areas with feet, inches, meters or centimeters and convert square feet, acres, square meters, hectares and square kilometers.
Switching systems clears entered values and restores any labeled editable examples in the new units. Individual dimension unit changes convert the entered length.
About the Square Footage Calculator
Square footage describes a two-dimensional surface, not its volume. Measure each side independently and select feet or inches in imperial mode, meters or centimeters in metric mode. For a rectangle multiply length by width; for a triangle multiply base by perpendicular height and divide by two. Break an irregular plan into simple shapes and add the areas.
For a circle enter a radius (center to edge) or select diameter (edge to edge). The formula is π × radius², so doubling the radius quadruples the area. An acre is 43,560 square feet and a hectare is 10,000 square meters. Optional cost uses price per square foot in imperial mode or price per square meter in metric mode and does not include waste.
Area is a starting point for material planning. The Flooring Calculator adds a cutting allowance and box count; the Tile Calculator counts individual tiles. For a poured slab, use the Concrete Calculator, which also needs depth to estimate volume.
Frequently asked questions
How many square feet are in one square meter?
One square meter is approximately 10.7639 square feet. Convert each length first, then multiply; do not use a linear conversion factor on an area.
Is a circle measured by radius or diameter?
Either can be entered. Radius is half the diameter; the calculator uses π times the radius squared.
Can I mix feet and inches?
Yes. Each dimension has a separate unit selector. Both are converted to meters before the area formula is applied.
Take this calculation further
Browse the other calculators collection for more tools in this subject.
For a related calculation, use Stair Calculator to calculate riser height, tread depth, and stringer length. Check IRC building code compliance. Alternatively, use Concrete Calculator to calculate concrete volume in cubic feet and yards for slabs, cylinders, and footings. Find bags needed.