Square Footage Calculator
Choose a rectangle, square, circle or triangle and enter dimensions in feet to calculate square feet, square meters and square yards.
Calculator arithmetic runs locally in your browser and does not require an API.
The interactive calculator loads here when JavaScript is enabled.
How to use Square Footage Calculator
For circles enter radius, not diameter. For triangles measure height perpendicular to the base. Split irregular rooms into shapes and add their areas separately.
Formula and method
Rectangle = length × width; square = side²; circle = π × radius²; triangle = base × perpendicular height/2.
Understanding the results
Multiply square feet by 0.09290304 for square meters or divide by nine for square yards. The result is geometric area, without waste, cutouts or material allowances.
Worked example
A rectangle 12 ft by 15 ft has 180 sq ft. That is 16.7225472 m² or 20 sq yd.
Check measurements before ordering materials.
Frequently asked questions
How do I measure an irregular room?
Divide it into supported shapes, calculate each separately and sum the areas; subtract cutouts separately.
What if I only know a circle’s diameter?
Divide the diameter by two and enter the resulting radius.
Is material waste included?
No. Calculate a separate allowance suited to your project before ordering materials.