Square Footage Calculator
Calculate Square Footage by Shape
Select your shape, enter the dimensions, choose your unit of measurement, and click Calculate to instantly get the area in square feet, square yards, square meters, and more.
What Is Square Footage?
Square footage (abbreviated as sq ft or ft²) is a unit of area measurement used primarily in the United States and Canada. It represents the total two-dimensional surface area of a space and is calculated by multiplying length by width — for rectangular areas. One square foot is equal to a square that measures exactly one foot on each side.
Square footage is one of the most commonly used measurements in real estate, home improvement, landscaping, and construction. Whether you're buying a home, planning a patio renovation, estimating flooring costs, or ordering materials like mulch or concrete, knowing the exact square footage of your project area is essential for accurate planning and budgeting.
Understanding square footage also helps you compare properties, estimate paint coverage, calculate heating and cooling requirements, and determine how much material you'll need for any outdoor or indoor project. Our Patio Cost Calculator and Concrete Calculator both rely heavily on square footage as a starting point for estimates.
How to Measure Square Footage
Measuring square footage accurately starts with the right tools: a measuring tape, a notepad, and a calculator (or this page!). The method varies depending on the shape of the area you're measuring.
Rectangle and Square Rooms or Areas
For rectangular or square spaces — the most common shape for rooms, patios, and lawns — the formula is straightforward:
Area = Length × Width
Measure the longest side (length) and the shortest side (width) in feet. Multiply them together to get square footage. For example, a patio that is 20 feet long and 15 feet wide has an area of 20 × 15 = 300 square feet.
For square areas, both sides are equal, so simply measure one side and multiply it by itself. A 12×12 foot garden square = 144 square feet.
Irregular Shapes — Break Into Rectangles
Many real-world spaces aren't perfect rectangles. An L-shaped patio, a room with an alcove, or a yard with a cutout requires a slightly different approach. The best strategy is to divide the irregular shape into smaller rectangles, calculate the area of each section separately, and then add them all together.
For example, if your patio is L-shaped, you might divide it into two rectangles: one measuring 12×10 ft (120 sq ft) and another measuring 8×6 ft (48 sq ft). The total area would be 120 + 48 = 168 square feet. If part of the space is subtracted (like a built-in planter box), measure that section and subtract it from the total.
Circular Areas
For circular patios, round garden beds, or fire pit areas, use the circle formula:
Area = π × r²
Where r is the radius (half the diameter) and π (pi) is approximately 3.14159. If you have a circular patio with a diameter of 16 feet, the radius is 8 feet and the area is 3.14159 × 8² = 201.06 square feet.
For triangular areas (like a corner garden bed), use: Area = 0.5 × base × height. This tool handles all three shapes automatically — just select the shape and enter your dimensions.
Common Square Footage Reference Chart
To put square footage in perspective, here's a helpful reference table showing typical sizes for common spaces:
| Space Type | Typical Size (sq ft) | Notes |
|---|---|---|
| Small Patio | 80 – 150 sq ft | Fits a bistro table and 2 chairs; good for apartments or townhomes |
| Average Patio | 150 – 400 sq ft | Accommodates dining table and lounge seating; most common size |
| Large Patio | 400 – 900+ sq ft | Full outdoor kitchen, dining, and lounge zones; estate-level |
| 1-Car Garage | 200 – 240 sq ft | Standard is 12×20 ft (240 sq ft) |
| Studio Apartment | 300 – 600 sq ft | Typical urban studio; all in one room |
| 2-Bedroom Home | 900 – 1,400 sq ft | Median U.S. 2BR home; varies widely by region |
| Football Field | 57,600 sq ft | 360×160 ft including end zones; 1.32 acres |
| Standard Parking Space | 160 – 180 sq ft | Typically 8×20 ft or 9×18 ft |
| Backyard Lawn (Average) | 5,000 – 10,000 sq ft | Suburban single-family home backyard |
| Basketball Court | 4,700 sq ft | NBA standard: 94×50 ft |
Square Footage to Other Units Conversion
Once you know your area in square feet, you may need to convert it to other units for ordering materials, comparing international measurements, or communicating with contractors who use metric. Here's a complete conversion reference:
| From | To | Multiply By | Example |
|---|---|---|---|
| Square Feet (ft²) | Square Yards (yd²) | ÷ 9 (or × 0.1111) | 300 sq ft = 33.33 sq yd |
| Square Feet (ft²) | Square Meters (m²) | × 0.0929 | 300 sq ft = 27.87 m² |
| Square Feet (ft²) | Square Inches (in²) | × 144 | 300 sq ft = 43,200 in² |
| Square Feet (ft²) | Square Centimeters (cm²) | × 929.03 | 300 sq ft = 278,709 cm² |
| Square Feet (ft²) | Acres | ÷ 43,560 | 43,560 sq ft = 1 acre |
| Square Yards (yd²) | Square Feet (ft²) | × 9 | 10 sq yd = 90 sq ft |
| Square Meters (m²) | Square Feet (ft²) | × 10.764 | 10 m² = 107.64 sq ft |
These conversions are especially useful when purchasing materials. For instance, mulch and topsoil are often sold by the cubic yard, which requires knowing your square footage plus depth. Our Mulch Calculator does this conversion automatically.
How to Use This Square Footage Calculator
This free calculator makes it easy to find the area of any rectangular, circular, or triangular space in multiple units simultaneously. Here's a quick walkthrough:
- Select your shape — Choose Rectangle/Square, Circle, or Triangle using the radio buttons at the top of the calculator.
- Enter your dimensions — Type in the length and width for rectangles, the radius or diameter for circles, or the base and height for triangles.
- Choose your unit — Select whether your measurements are in feet, inches, yards, meters, or centimeters. The calculator converts everything automatically.
- Click Calculate — The result area will instantly display the area in square feet, square yards, square meters, square inches, and square centimeters.
The calculator handles all the math for you — including unit conversions and the correct formula for each shape. Results are rounded to two decimal places for readability, but all conversions are mathematically precise.
For larger projects involving multiple shapes, simply calculate each section separately and add the results together. If you're planning a patio or hardscape project, you can then plug your square footage total into the Patio Cost Calculator or Concrete Calculator to estimate material quantities and costs.
Area Conversion Factors
| To Convert From | To | Multiply By |
|---|---|---|
| Square Feet (sq ft) | Square Yards (sq yd) | 0.11111 |
| Square Feet (sq ft) | Square Meters (sq m) | 0.092903 |
| Square Feet (sq ft) | Square Inches (sq in) | 144 |
| Square Feet (sq ft) | Acres (ac) | 0.000022957 |
Frequently Asked Questions
How do I calculate the square footage of an irregularly shaped room?
Break the irregular shape into smaller rectangles or squares. Measure each section's length and width, calculate the area of each (length × width), and add all the areas together. Subtract any sections that don't count, such as built-in closets that were measured as part of the room but belong to a different calculation.
How many square feet is a 12×12 room?
A room that is 12 feet long by 12 feet wide has an area of 144 square feet (12 × 12 = 144). This is also equal to 16 square yards, or approximately 13.38 square meters.
Why do contractors add extra square footage when ordering materials?
Contractors typically add 10–15% to the calculated square footage as a waste factor. This accounts for cuts, trimming around edges, irregular shapes, breakage during installation, and future repairs. For tile and pavers, a 10% overage is standard; for complex patterns like herringbone, 15% is recommended. Always order extra — running out mid-project and needing a second order can result in color or texture mismatches.
How do I convert square feet to square yards for carpet ordering?
Divide the square footage by 9 to get square yards. For example, a 300 sq ft room needs 300 ÷ 9 = 33.33 square yards of carpet. Carpet is almost always sold by the square yard in the U.S., so this conversion is essential when getting flooring quotes.
What is the difference between square feet and linear feet?
Square feet measure area (a two-dimensional surface), while linear feet measure length (a single dimension). For example, a fence might be 100 linear feet long, but if that fence has a height of 6 feet, the total area of the fence would be 600 square feet. Linear feet are used for fencing, baseboards, trim, and lumber, while square feet are used for flooring, walls, and outdoor surfaces.
How accurate is this square footage calculator?
This calculator is mathematically precise using standard formulas. The accuracy of your result depends entirely on the accuracy of your measurements. Always measure twice, and for large areas consider using a laser measuring tool for best results. Remember that real-world spaces often have minor variations, so adding a small buffer (5–10%) is always wise when ordering materials.
- ISO Standards - ISO 80000-3 Quantities and units for space and time.
- ANSI Standards - Standard measurements for property building footprint calculations.