Square Footage Calculator
Calculate square footage for any shape: rectangles, squares, triangles, circles, trapezoids, and L-shapes. Results in square feet, square yards, square meters, and acres. Enter an optional cost per square foot to estimate project material cost.
Formulas, assumptions, and rounding are documented in our calculator methodology.
Shape
Area
120.00
square feet
Area in All Units
- Square Feet
- 120.00 sq ft
- Square Yards
- 13.3333 sq yd
- Square Meters
- 11.1484 m²
- Acres
- 0.002755 acres
Room Areas Mode: Floor, Ceiling, and Walls
Switch to the Room Areas tab and enter length, width, and ceiling height to instantly get floor area (length × width), ceiling area (same), gross wall area (2 × (length + width) × height), and paintable wall area after deducting doors and windows. Door deductions use a standard 3 ft × 7 ft opening (21 sq ft); window deductions use a standard 3 ft × 5 ft opening (15 sq ft). Use floor area for flooring and tile, paintable wall area for paint, and ceiling area for ceiling paint and drywall.
Area Formulas by Shape
Rectangle or square: A = length × width. Triangle: A = 0.5 × base × height. Circle: A = π × radius² (where radius = diameter ÷ 2). Trapezoid: A = 0.5 × (side1 + side2) × height (the two parallel sides plus the perpendicular height between them). L-shape: divide into two rectangles, calculate each, then add. All measurements must be in the same unit (feet) before calculating.
Square Feet, Square Yards, Square Meters, and Acres
1 square yard = 9 square feet (3 × 3). 1 square meter ≈ 10.764 square feet. 1 acre = 43,560 square feet. Carpet and some flooring are sold by the square yard; most US flooring and paint are sold by the square foot; international and scientific measurements use square meters; land area is often expressed in acres.
Estimating Project Cost from Square Footage
Enter a cost per square foot to get an instant material cost estimate. Common reference prices: luxury vinyl plank flooring $2–$5/sq ft, hardwood $5–$10/sq ft, ceramic tile $1–$4/sq ft, carpet $1–$4/sq ft, exterior paint coverage (one coat) about 350 sq ft/gallon at $30–$60/gallon. These are material costs only — labor, adhesive, grout, primer, and tools are additional.
Measuring Tips for Accurate Results
Measure twice before calculating. For rooms, measure at floor level along the longest walls. If walls are not perfectly parallel (common in older homes), measure at the widest and narrowest points and use the average. Convert inches to decimal feet by dividing by 12 (e.g., 4 inches = 0.333 ft). Include closets and alcoves if they will receive the same flooring or paint.
Frequently Asked Questions
- Measure the length and width of the room in feet. Multiply them together: sq ft = length × width. For an irregular room, divide it into rectangles, calculate each section separately, and add the results together.
- One acre = 43,560 square feet. One acre is also equal to 4,840 square yards or about 4,047 square meters. A standard football field (including end zones) is about 1.32 acres.
- Multiply square feet by 0.0929 to get square meters. Example: 1,200 sq ft × 0.0929 = 111.5 m². To go the other direction, multiply square meters by 10.764 to get square feet.
- Divide the L-shape into two rectangles. Measure each rectangle's length and width, calculate each area separately, then add them together. There are usually two ways to divide an L-shape — both give the same total area.
- Square feet measure area (a two-dimensional surface). Linear feet measure length (a single dimension). Flooring and paint are sold by square feet. Baseboards, crown molding, and fencing are sold by linear feet (the perimeter of a room, not the area).
- A trapezoid has two parallel sides (bases) and a height measured perpendicular to both bases. Formula: A = ½ × (base1 + base2) × height. For example, a trapezoid with parallel sides of 10 ft and 14 ft and a height of 8 ft has an area of ½ × (10 + 14) × 8 = 96 sq ft.
- Multiply the total square footage by the cost per square foot of your material. For example, 500 sq ft × $3.50/sq ft = $1,750 in materials. Always add 10–15% for waste and cuts. Labor costs are separate and vary by region and project type.
- Measure the radius (half the diameter) in feet. Use the formula: A = π × radius². For example, a circular patio with a 7-foot radius has an area of π × 7² ≈ 153.9 sq ft. If you only know the diameter, divide it by 2 to get the radius.
- Wall area = perimeter × ceiling height. Perimeter = 2 × (length + width). Example: a 12 ft × 10 ft room with 9 ft ceilings has a perimeter of 44 ft and a gross wall area of 44 × 9 = 396 sq ft. Subtract openings: one standard door (3×7 ft = 21 sq ft) and two windows (3×5 ft = 15 sq ft each) reduce paintable wall area by 51 sq ft, leaving 345 sq ft. Use the Room Areas tab for automatic calculation.
- Floor: 12 × 10 = 120 sq ft. Ceiling: 120 sq ft. Gross wall area: 2 × (12 + 10) × 9 = 396 sq ft. With one door (21 sq ft) and two windows (30 sq ft total), paintable wall area ≈ 345 sq ft. Total (floor + ceiling + paintable walls) ≈ 585 sq ft.