Square Footage Calculator
Calculate area for any room or lot shape — rectangle, triangle, circle, L-shape, or trapezoid — with automatic unit conversions.
Select Shape
Formula: Length × Width
Enter to calculate total material or project cost.
Area
300.00 sqft
33.33 sq yd · 27.87m²
| Square Feet | 300.00 sqft |
| Square Yards | 33.33 sq yd |
| Square Meters | 27.87 m² |
Standard area formulas. Rectangle: L × W. Triangle: ½ × base × height. Circle: π × r². L-shape: total bounding rectangle minus the cutout rectangle. Trapezoid: ½ × (side1 + side2) × height. 1 acre = 43,560 sqft. 1 sqft = 0.0929 m². Acres displayed only for areas ≥ 1,000 sqft.
Frequently Asked Questions
How do I calculate square footage of an irregular room?
Break the room into simple rectangles, calculate each one separately, then add the areas together. For most L-shaped or T-shaped rooms, this works perfectly — just make sure your measurements don't overlap. Use the L-Shape mode above for the most common irregular room type.
How many square feet is an acre?
One acre is exactly 43,560 square feet. A standard American football field (including end zones) is about 1.32 acres or roughly 57,600 sqft. A quarter-acre residential lot — common in suburban subdivisions — is 10,890 sqft.
How do I convert square feet to square yards?
Divide by 9. One square yard = 9 square feet (because 1 yard = 3 feet, and 3 × 3 = 9). This matters most for carpet and flooring sold by the square yard. A 12×15 room is 180 sqft or 20 square yards.
What's the easiest way to measure a room?
For rectangular rooms, measure the longest length wall to wall, then the widest width wall to wall. Measure at floor level. For irregular shapes, sketch it out on paper first and break it into rectangles. A laser distance measurer makes this faster and more accurate than a tape measure for larger spaces.