Free Square Footage Calculator
Calculate square footage for rooms, yards, flooring, roofing, and more. Supports rectangles, circles, triangles, and trapezoids. Free and instant.
Square Feet
300 ft²
Square Yards
33.33 yd²
Square Meters
27.87 m²
Acres
0.0069
Formula
Area = Length × WidthHow to Calculate Square Footage
Square footage is one of the most commonly needed measurements in everyday life. Whether you're buying flooring, painting walls, planning a garden, listing a home for sale, or estimating construction materials, knowing how to calculate square footage is essential.
The basic formula is simple: Length × Width = Square Feet. But real-world spaces aren't always perfect rectangles. That's why this calculator supports four shapes: rectangles, circles, triangles, and trapezoids.
Common Square Footage References
- Small bedroom: 100-150 sq ft (10×10 to 10×15)
- Master bedroom: 200-350 sq ft (14×14 to 17×20)
- Living room: 200-400 sq ft
- One-car garage: 200-250 sq ft (10×20 to 12×22)
- Two-car garage: 400-600 sq ft (20×20 to 24×24)
- Average US home: 2,300 sq ft
- Studio apartment: 400-600 sq ft
- Basketball court: 4,700 sq ft
- Tennis court: 2,808 sq ft
- One acre: 43,560 sq ft
Square Footage for Home Projects
Knowing your square footage is the first step for almost any home improvement project. For flooring, measure the room and add 10% for waste and cuts. For painting, multiply wall height by wall length to get wall square footage (subtract windows and doors). For roofing, ground-level square footage needs to be adjusted for roof pitch.
When buying materials, always round up — it's better to have a little extra than to make another trip to the store. Most flooring and tile retailers recommend ordering 10-15% more than your calculated square footage.
Square Footage in Real Estate
In real estate, square footage directly affects home value. The price per square foot varies wildly by location — from $100/sq ft in rural areas to $1,000+/sq ft in Manhattan. When comparing homes, price per square foot is one of the best ways to evaluate value. A 2,000 sq ft home at $300,000 is $150/sq ft, while a 1,500 sq ft home at $250,000 is $167/sq ft — the bigger home is actually the better deal per square foot.
Note that "livable square footage" typically excludes garages, unfinished basements, and outdoor areas. When listing or buying a home, always clarify what's included in the square footage measurement.
Frequently Asked Questions
How do I calculate square footage of a room?
Measure the length and width of the room in feet, then multiply them together. A room that is 12 feet long and 10 feet wide is 120 square feet (12 × 10 = 120 sq ft). For oddly shaped rooms, break them into rectangles, calculate each one, and add them together.
How many square feet is a 12x12 room?
A 12×12 room is 144 square feet (12 × 12 = 144). This is a standard bedroom size. For reference, a 10×10 room is 100 sq ft, a 15×15 room is 225 sq ft, and a 20×20 room is 400 sq ft.
How do I convert square feet to square yards?
Divide square feet by 9. There are 9 square feet in 1 square yard (3 ft × 3 ft = 9 sq ft). So 300 square feet = 33.3 square yards. This is useful when buying carpet, which is often priced per square yard.
How do I calculate square footage for an irregular shape?
Break the irregular area into simple shapes (rectangles, triangles, circles). Calculate the area of each shape separately, then add them all together. For L-shaped rooms, split them into two rectangles. For curved areas, use the circle formula for the curved section.
How many square feet is an acre?
One acre is 43,560 square feet. For reference, an acre is roughly the size of a football field without the end zones (which is 48,000 sq ft). A half-acre lot is 21,780 sq ft, and a quarter-acre is 10,890 sq ft.