Square Footage Calculator
Measure any rectangular space in seconds. Enter length and width to get square footage, square yards, and acreage for flooring, painting, or land measurement.
Basic Square Footage Formula
Square footage is the area enclosed by a rectangle. The formula is length times width, both measured in feet. A room 12 feet by 15 feet contains 180 square feet.
Always measure at the widest point. Walls are rarely perfectly straight, and a few inches can add up over the length of a room. For real estate appraisals, measure to the outside of exterior walls and the center of shared interior walls.
Round measurements to the nearest inch for residential projects. Precision beyond that does not matter for flooring or paint. Commercial and industrial work may require tighter tolerances depending on code and design specs.
Converting Between Square Feet and Square Yards
Square yards are still used for carpet, sod, and some paving materials. One linear yard equals 3 feet, so one square yard is 3 Γ 3 = 9 square feet. Divide your square footage by 9 to get square yards.
Suppliers often price by the square yard but install by the square foot. Always confirm which unit the quote uses. A price of $5 per square yard sounds cheap until you realize it equals $45 per square foot.
This calculator shows both units to avoid confusion. Check the invoice unit and compare apples to apples when shopping for materials or services.
Measuring Irregular or Multi-Room Spaces
L-shaped rooms and open floor plans break down into rectangles. Measure each section separately, calculate the area, and add the results. A living room might be 12 Γ 20 (240 sq ft) plus an alcove 6 Γ 8 (48 sq ft) for a total of 288 square feet.
Round or angled spaces require different formulas. Circles use ΟrΒ², triangles use Β½ Γ base Γ height, and trapezoids have their own calculations. For complex shapes, an architect or surveyor may use CAD software.
When estimating materials, add 5 to 10 percent for waste. Cuts, mistakes, and irregular layouts consume extra flooring, tile, or paint. Better to return unused material than run short mid-project.
Frequently Asked Questions
How do I calculate square footage?
Multiply the length by the width. A room that is 10 feet long and 12 feet wide has 120 square feet.
What is the difference between square feet and square yards?
One square yard equals 9 square feet. Carpet and some flooring materials are sold by the square yard, while most construction uses square feet.
How many square feet are in an acre?
One acre equals 43,560 square feet. This calculator converts to acres automatically for large plots.
Can I measure irregular shapes?
For L-shaped or complex rooms, break the space into rectangles, calculate each area separately, then add them together. The multi-room mode helps with this.
Do I include closets in square footage?
For real estate purposes, finished closets with standard ceiling height count toward total square footage. Unfinished storage areas and spaces under stairs usually do not.