Square Footage Calc
Calculate total square footage for rooms, floors, and properties. Supports feet, inches, meters, and yards with built-in material cost estimation. Free for homeowners and contractors.
Space Dimensions
Optional: Material Cost
Useful for flooring, painting, or contractor estimates.
Results
Total Area
0
Square Feet
Conversions
How to Calculate Square Footage
Square footage (abbreviated as sq ft or ft²) is a unit of area measurement in the Imperial system used primarily in the United States, Canada, and the United Kingdom. It represents the area of a square with sides measuring one foot (12 inches or 0.3048 meters).
The fundamental formula is straightforward: Area = Length × Width. For a rectangular room measuring 15 feet long by 12 feet wide, the total area is 180 square feet. For spaces measured in different units, our calculator handles the conversion automatically using standard factors defined by the National Institute of Standards and Technology (NIST).
Common Area Conversion Factors
Sq Ft → Sq Meters
1 ft² = 0.0929 m²
Multiply sq ft by 0.092903
Sq Ft → Sq Yards
1 ft² = 0.1111 yd²
Divide sq ft by 9
Sq Ft → Acres
43,560 ft² = 1 acre
Divide sq ft by 43,560
Real-World Applications
- Flooring Projects: Measure all rooms and add 10% waste. Home Depot and Lowe's sell flooring by the square foot, making this calculator essential for accurate budgeting.
- Painting Estimates: One gallon of paint covers approximately 350-400 sq ft on average. Calculate wall area (height × width × 4 walls minus doors/windows) to determine gallons needed.
- Real Estate Listings: The American National Standards Institute (ANSI) Z765 standard defines how to measure finished square footage for home appraisals and MLS listings.
- HVAC Sizing: A general rule is 20 BTU per square foot for air conditioning. A 1,500 sq ft home needs approximately a 30,000 BTU (2.5-ton) AC unit.
Irregular Room Shapes
Not every room is a perfect rectangle. Here's how to handle common irregular shapes:
- L-Shaped Rooms: Split into two rectangles by drawing an imaginary line, measure each, and add them as separate areas in our tool.
- Triangular Areas: Use the formula
Area = ½ × base × height, then convert to square footage. - Circular Areas: Use
Area = π × r²(Pi times the radius squared). For a room with a 10-foot diameter, the radius is 5 ft, giving 78.54 sq ft. - Closets & Alcoves: Measure them separately and add as a new area entry in the calculator.
Frequently Asked Questions
How do I calculate square footage?
Multiply the length of a space by its width: Area = Length × Width. A room 12 feet by 10 feet = 120 square feet. For irregular shapes, break the space into rectangles, calculate each, and add together.
How many square feet are in an acre?
One acre equals exactly 43,560 square feet, or approximately 4,047 square meters—about 90% of an American football field.
How do I convert square feet to square meters?
Multiply by 0.092903. For example, 500 sq ft × 0.092903 = 46.45 m². Our calculator does this automatically.
How much flooring do I need?
Measure your total square footage and add 10% for waste from cuts and mistakes. If your area is 800 sq ft, order 880 sq ft of material.
How do I calculate the square footage of an L-shaped room?
Break the L-shape into two separate rectangles. Measure each, calculate their areas, and add them together using our multi-area calculator.
Does the calculator store my measurements?
No. All calculations run in your browser via JavaScript. Your room dimensions and cost data are never sent to any server.
The tools and calculators provided on The Simple Toolbox are intended for educational and informational purposes only. They do not constitute financial, legal, tax, or professional advice. While we strive to keep calculations accurate, numbers are based on user inputs and standard assumptions that may not apply to your specific situation. Always consult with a certified professional (such as a CPA, financial advisor, or attorney) before making significant financial or business decisions.
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