About the Square Footage Calculator
This square footage calculator finds the area of a room, yard, deck, lot or any surface. Pick the shape — rectangle, L-shape, circle, triangle or trapezoid — enter the measurements in feet, inches, yards, meters or centimeters, and it returns the area in square feet along with square meters, square yards, square inches and acres. Add a price per square foot to turn the area into a cost.
It is useful for pricing flooring, carpet, tile, paint, sod or concrete; for checking a listing’s stated living area; and for comparing rent per square foot. For irregular rooms, split the space into simple shapes, calculate each one, and add them together — the L-shape option does that for the most common case.
All measurements should use the same unit. The quantity field multiplies the result, which is handy for several identical rooms or deck boards.
With the default inputs, the area is 180 sq ft. Change any value above to recalculate instantly.
How to use the square footage calculator
- 1Choose the shape that best matches the space.
- 2Select the unit you measured in.
- 3Enter the measurements (split L-shaped rooms into two rectangles).
- 4Set a quantity for identical rooms, and a price per sq ft if you want a cost.
- 5Read the area in square feet, square meters, square yards and acres.
Formula and method
Each measurement is converted to feet first, so the area comes out in square feet regardless of the unit you measured in. A rectangle is length × width; an L-shaped room is split into two non-overlapping rectangles that are added together; a circle is π × radius²; a triangle is half of base × perpendicular height; and a trapezoid is the average of its two parallel sides × the height between them.
The result is multiplied by the quantity, then converted with exact factors: 1 sq ft = 0.09290304 m² = 144 in², 9 sq ft = 1 sq yd and 43,560 sq ft = 1 acre.
- L, W
- Length and width
- D
- Circle diameter
- b, h
- Triangle base and perpendicular height
- a, b
- Trapezoid parallel sides
Worked examples
15 × 12 ft bedroom
A 15 × 12 ft room is 180 square feet, which is 16.72 m² or 20 square yards. At $4 per sq ft of flooring that area costs about $720 before waste.
L-shaped living area
Split the room into a 20 × 12 ft section (240 sq ft) and a 10 × 8 ft section (80 sq ft). Together they make 320 square feet.
10 ft round patio
The radius is 5 ft, so the area is π × 5² = 78.54 square feet, or about 7.3 m².
4 × 5 m room measured in meters
A 4 × 5 m room is 20 m². Dividing by 0.0929 converts that to 215.28 square feet.
Frequently asked questions
How do you calculate square footage?+
For a rectangle, multiply the length by the width in feet. A 15 ft by 12 ft room is 15 × 12 = 180 square feet. Split odd-shaped rooms into rectangles and add them up.
How do I calculate square feet from inches?+
Multiply length × width in inches to get square inches, then divide by 144. For example 60 × 48 inches = 2,880 in² = 20 sq ft.
How many square feet are in a square meter?+
One square meter is about 10.764 square feet, and one square foot is 0.0929 square meters.
How do I find the square footage of a house?+
Measure each room or the exterior footprint of each floor and add them together. Official living area standards usually count finished, heated space and exclude garages and unfinished basements.
How many square feet are in an acre?+
An acre is exactly 43,560 square feet, or about 4,047 square meters — roughly 208.7 × 208.7 feet.