Square Footage Calculator
Calculate the area of any shape in square feet with unit conversions and cost estimates.
Enter a price to get a total cost estimate
Unit Conversions
| Unit | Area |
|---|---|
| Square Feet | 0 |
| Square Meters | 0 |
| Square Yards | 0 |
| Acres | 0 |
Tip: For irregularly shaped rooms, divide the space into smaller rectangles and triangles, calculate each separately, then add the results together.
How to Calculate Square Footage Accurately
Square footage is one of the most fundamental measurements in real estate, construction, and home improvement. It represents the area of a two-dimensional surface measured in square feet, where one square foot equals a space that is one foot long by one foot wide. Whether you are buying a home, ordering materials for a renovation, or planning a landscaping project, knowing how to calculate square footage correctly saves time, money, and frustration. Errors in measurement can lead to ordering too much or too little material, inaccurate property valuations, or project delays.
Formulas for Common Shapes
Rectangular and square spaces are the simplest to measure: multiply the length by the width. A room that is 12 feet long and 10 feet wide has an area of 120 square feet. For triangular areas, multiply the base by the height and divide by two. A triangle with a 20-foot base and a 10-foot height covers 100 square feet. Circular areas use the formula pi times the radius squared. A circular patio with a 6-foot radius covers approximately 113 square feet. Trapezoids, which have two parallel sides of different lengths, use the formula: add the two parallel sides, multiply by the height, and divide by two. If the parallel sides are 15 and 25 feet with a height of 10 feet, the area is 200 square feet. When your measurements are in inches, divide each measurement by 12 before multiplying, or calculate in square inches and divide the result by 144 to convert to square feet.
Quick Conversion Reference
1 square foot = 144 square inches = 0.0929 square meters
1 square yard = 9 square feet
1 acre = 43,560 square feet
1 square meter = 10.764 square feet
To convert square feet to square meters, multiply by 0.0929. To convert square meters to square feet, multiply by 10.764.
Measuring Irregularly Shaped Rooms
Most real-world rooms are not perfect rectangles. L-shaped rooms, rooms with alcoves, bay windows, or angled walls require a divide-and-conquer approach. Break the space into smaller rectangular or triangular sections, measure and calculate each one independently, then add all the areas together. For an L-shaped room, divide it into two rectangles, calculate each area, and sum them. For rooms with curved walls or unusual angles, approximate the curves with straight lines and triangles to get a close estimate. When precision is critical, consider using a laser distance measurer, which provides accuracy to within an eighth of an inch and is much faster than a traditional tape measure for large or complex spaces.
Why Accurate Square Footage Matters
In real estate, square footage directly affects property valuation and pricing. Homes are commonly compared on a price-per-square-foot basis, so even small errors in measurement can translate to thousands of dollars in over- or under-valuation. For construction and renovation projects, accurate square footage determines how much flooring, paint, tile, carpet, or other materials to purchase. Ordering 10 percent too little means a second trip to the store and potential delays; ordering 30 percent too much wastes money on unused materials. For paint, one gallon typically covers about 350 to 400 square feet. For flooring, most professionals recommend ordering 5 to 10 percent extra to account for cuts and waste. When hiring contractors, accurate measurements help you evaluate quotes and ensure you are being charged fairly for the actual work area. Always measure yourself rather than relying on estimates, and double-check critical measurements before placing material orders.