Square Footage Calculator

Calculate Square Footage Accurately

Whether you're ordering flooring, estimating paint, planning a garden, measuring a room for furniture, or calculating property size, knowing the exact square footage prevents costly over-ordering and embarrassing under-ordering. Our calculator handles rectangular, L-shaped, triangular, and circular areas with automatic unit conversion between square feet and square meters.

Common formulas: Rectangle: Length × Width. A 12' × 15' room = 180 sq ft. Triangle: (Base × Height) ÷ 2. A garden with 10' base and 8' height = 40 sq ft. Circle: π × radius². A circular patio with 6' radius = 113.1 sq ft. L-shaped rooms: divide into two rectangles and add.

Practical Applications

Flooring: Calculate room area, then add a 10% waste factor for cuts and mistakes. A 200 sq ft room needs 220 sq ft of flooring material. For diagonal installation, add 15%. Tile installations may need 10–15% extra depending on pattern complexity.

Paint: One gallon covers approximately 350–400 sq ft with one coat. Calculate wall area: perimeter × wall height, then subtract windows and doors. A 12' × 15' room with 8' ceilings: perimeter = 54 feet × 8 = 432 sq ft of wall area. Subtract ~50 sq ft for windows/doors = 382 sq ft. Two coats needs approximately 2 gallons.

Mulch and landscaping: 1 cubic yard of mulch covers 162 sq ft at 2" depth, 108 sq ft at 3" depth. Calculate your garden bed area, choose desired depth, and divide by coverage per yard. A 500 sq ft bed at 3" depth needs approximately 4.6 cubic yards.

Carpet and rugs: Carpet is sold by the square yard (1 sq yd = 9 sq ft). A 200 sq ft room needs approximately 22.2 sq yards. Add 10% for seams and cuts = 24.4 sq yards.

Property measurement: 1 acre = 43,560 sq ft. A quarter-acre lot = 10,890 sq ft. A typical American suburban house lot ranges from 5,000–15,000 sq ft (0.11–0.34 acres).

Measuring Irregularly Shaped Spaces

L-shaped rooms: Divide into two rectangles. If the L is 20' × 12' with a 10' × 8' extension, calculate each rectangle separately (240 sq ft + 80 sq ft = 320 sq ft total).

Rooms with alcoves or bump-outs: Measure the main rectangle, then add the area of each alcove. Subtract closet areas if they're not being covered.

Curved walls: Approximate curves as a series of straight segments, or calculate the circular segment area. For a room with a bay window curve, measure the chord length and the depth of the curve, then use the circular segment formula.

Outdoor spaces: For lawns and gardens with irregular boundaries, the easiest method is to break the area into simple shapes (rectangles, triangles), calculate each, and sum. For very irregular shapes, use the grid method: overlay a grid of 1-foot squares and count how many fall inside the boundary.