How to use the square footage calculator
- 1 Choose the shape: rectangle, circle, triangle, trapezoid or L-shape.
- 2 Enter the measurements and choose the unit.
- 3 Add a waste percentage and a price per square foot if you like.
- 4 Read the square footage, the metric area and the cost.
Worked example
A rectangular room 15 feet by 12 feet. The area is 15 × 12 = 180 square feet, which is 16.72 square meters or 20 square yards. With 10% extra for flooring waste you would order 198 square feet; at $4 per square foot that is $792.
Measuring rooms and yards
- Measure wall to wall at floor level.
- Split odd shapes into rectangles and add them.
- Round up to the next inch.
- Add 10% waste for flooring and tile.
Order gravel with the Gravel Calculator and concrete with the Concrete Calculator, and convert with Square Feet to Square Meters. For round areas use the Circumference Calculator; to cool the room, size an air conditioner with the BTU Calculator.
How it works: Each measurement is converted to feet first, so inches, yards and meters all give square feet. The shape formula is applied, the waste percentage is added, and the result is converted to square meters, square yards and acres. Cost uses the area with waste.
Features
Five shapes
Rectangle, circle, triangle, trapezoid and L-shaped rooms.
Any unit
Feet, inches, yards or meters in; square feet, meters, yards and acres out.
Cost and waste
Waste allowance and price per square foot.
When to use it
Flooring and carpet
Order the right amount with 10% extra for cuts.
Gravel and mulch
Use the area to order material with the Gravel Calculator.
Concrete patios
Find the volume with the Concrete Calculator.
Converting area
Change units with the Square Feet to Square Meters converter.
Related Construction tasks
Frequently asked questions
How do you calculate square footage?
For a rectangle, multiply length by width in feet. A room 15 feet by 12 feet is 180 square feet.
How do I find the square footage of an L-shaped room?
Split it into two rectangles, find each area and add them. Enter both rectangles with the L-shape option.
How do I calculate the area of a circle in square feet?
π × radius². A circle 10 feet across has a radius of 5 feet and an area of 78.5 square feet.
How do I convert inches to square feet?
Multiply length by width in inches and divide by 144. Or enter inches and the calculator converts.
How many square feet is a 12×12 room?
144 square feet.
How much extra flooring should I buy?
Usually 5% to 10% for straight layouts and 15% for diagonal or patterned layouts and tile.
How many square feet are in a square meter?
10.764. One square yard is 9 square feet, and an acre is 43,560 square feet.
Do I include closets in a room's square footage?
For flooring, yes, if you are covering them. For home listings, rules vary; usually only finished, heated living space counts.
How do I find the square footage of a house?
Measure each room or the outside walls of each floor and add them up. Garages and unfinished basements usually are not counted.
How do I calculate the cost of a project per square foot?
Multiply the area (with waste) by the price per square foot. 180 square feet at $4 is $720.
How many square feet is a 10×12 room?
120 square feet.
How do I calculate the square footage of walls for paint?
Multiply each wall's width by the ceiling height, add them, and subtract doors (about 20 sq ft) and windows (about 15 sq ft).
Built and reviewed by Hamza Farooq, founder and lead developer
· Last updated
· How we check our tools
· Report a problem