Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this square footage calculator
Calculate the area of a rectangle, triangle, or circle. Convert square feet to square meters, square yards, and acres.
How the calculation works
Rectangle area = length × width. Triangle area = base × perpendicular height ÷ 2.
Circle area = π × radius². Multiply square feet by 0.09290304 for square meters; divide by 9 for square yards or 43,560 for acres.
Worked example
A 12 × 10 ft rectangle has 120 sq ft, equivalent to 11.15 m² or 13.33 sq yd.
Limits and assumptions
Calculates geometric area from the entered dimensions. For irregular footprints, add non-overlapping sections. No ordering waste is included.
Frequently asked questions
Do I enter circle diameter or radius?
Radius, which is half the diameter.
How do I measure an L-shaped room?
Divide it into two non-overlapping rectangles and add their areas.
Is area the same as perimeter?
No. Area measures surface coverage; perimeter measures the distance around the edge.