Calculate area in square feet for any shape — rectangles, circles, and triangles. Perfect for flooring, painting, and construction projects.
Select a shape and enter dimensions to calculate the area.
A square footage calculator computes the area of a space in square feet (sq ft or ft²). Whether you're planning a home renovation, ordering flooring materials, or estimating paint coverage, knowing the exact square footage is essential for budgeting and purchasing the right quantity of materials. According to the National Association of Home Builders (NAHB), the average new American home is approximately 2,500 square feet.
Square footage measurements are the standard in the United States real estate market and construction industry. They directly impact property valuations, rental pricing, and material costs. For volume-based projects requiring depth measurements, check our Cubic Yards Calculator.
Example: A room measures 12 feet by 15 feet
Area = 12 × 15 = 180 square feet
Example: A circular patio with a 10-foot diameter (radius = 5 ft)
Area = 3.14159 × 5² = 3.14159 × 25 = 78.54 square feet
Example: A triangular garden bed with base 8 ft and height 6 ft
Area = 0.5 × 8 × 6 = 24 square feet
When working with different measurement units, use these conversion factors (sourced from NIST — National Institute of Standards and Technology):
Our Unit Converter can help with additional conversions between measurement systems.
For L-shaped or irregular rooms, break the space into rectangles, calculate each area separately, then add them together. For very complex shapes, Math is Fun's area guide recommends dividing into simple geometric shapes (rectangles, triangles, semicircles) and summing the areas.
One acre contains 43,560 square feet. To visualize this, an acre is approximately 90% of an American football field (which is 48,000 sq ft including end zones).
Measure the width and height of each wall, multiply them together, then add all wall areas. Subtract the area of doors and windows for painting estimates.
Linear feet measures length in a straight line (one dimension), while square feet measures area (two dimensions: length × width). You need both dimensions for square footage.
A 12×12 room is 144 square feet. With the recommended 10% waste factor, you'd need about 158 sq ft of flooring material.