Calculate Square Feet Calculator: Formula for Any Shape
To calculate square feet, multiply length by width when both are measured in feet, so a 12 by 10 foot room is 120 square feet. Squares, circles, triangles and L-shaped rooms each need a different formula or a bit of splitting into pieces, and the square footage calculator below does all six shapes at once, with the result also shown in square yards and square meters.
Key takeaways
- Square feet = length (ft) x width (ft) for any rectangle or room; a 12x12 room is 144 sq ft and a 10x10 room is 100 sq ft.
- For circles, triangles, basements and multi-room jobs, split the space into simple shapes, find each area, then add or subtract the pieces.
- Divide square feet by 9 for square yards, or multiply by 0.092903 for square meters.
- The square-footage calculator can apply an entered price per square foot to measured area; it does not determine a contractor's scope, rate or property appraisal.
- Google Maps and Google Earth give rough exterior estimates only; real estate agents and appraisers measure official square footage to the ANSI Z765-2021 standard.
How to calculate square feet for a rectangle or room
To calculate square feet for a rectangle or room, multiply length by width, with both measurements in feet. A 12 by 10 foot bedroom is 12 x 10, which is 120 square feet of surface area.
Area (ft2) = Length(ft) x Width(ft)Inches get entered as a decimal of a foot: 6 inches is 0.5 feet, so a wall measuring 12 feet 6 inches is 12.5 feet. Mixing feet and inches without converting is the most common source of a wrong total.
For a fast result across six shapes and multiple rooms at once, enter your dimensions in the square footage calculator, which also converts the area to square yards and square meters and can price it per square foot.
Square footage for common room, garage and lot sizes
Multiplying length by width gets tedious across several rooms or a full floor plan. The table below covers the room and garage sizes people look up most, from a small bedroom to a two-car garage.
| Space size | Square feet | Square yards |
|---|---|---|
| 10 x 10 ft | 100 | 11.11 |
| 10 x 12 ft | 120 | 13.33 |
| 12 x 12 ft | 144 | 16.00 |
| 12 x 14 ft | 168 | 18.67 |
| 14 x 16 ft | 224 | 24.89 |
| 20 x 20 ft (2-car garage) | 400 | 44.44 |
| 24 x 24 ft | 576 | 64.00 |
So a 12x12 room is 144 square feet, and a 10x10 room is 100 square feet, the two sizes people search for most since they match a typical bedroom and a small patio or shed pad. A standard two-car garage at 20 by 20 feet comes out to 400 square feet.
How to calculate square feet for a square, circle or triangle
A square uses one measurement: side times side. A 10 foot square side is 10 x 10, or 100 square feet, the same result as a 10x10 rectangle.
A circle, like a round patio or fire pit pad, is pi times the radius squared, where the radius is half the diameter. A 12 foot diameter circle has a 6 foot radius, so the area is pi x 6 x 6, about 113.1 square feet.
Circle Area (ft2) = π x (Diameter ÷ 2)2A triangle with a right-angle height is half of base times height. A 3 foot base with a 4 foot height gives 0.5 x 3 x 4, which is 6 square feet, the same triangle used in the classic 3-4-5 right-angle check. The perimeter alone will not give you the area; you need a base and height, or all three sides.
Once you have the square footage of a patio or slab area, the concrete calculator turns it into cubic yards and bags once you add the pour thickness.
Square footage for L-shaped rooms, basements and multiple rooms
Do not try to force an L-shaped or irregular room into one formula. Split it into two or more rectangles, or a rectangle plus a triangle for a room with a bay window, and calculate each piece on its own.
Add the square footage of every piece for the total, then subtract anything you are not covering, like a fireplace hearth or a kitchen island footprint, by calculating that area separately.
To total multiple rooms into one project, such as tile for a kitchen, hallway and two bathrooms, calculate each room's square footage on its own and add the totals together before ordering material.
A finished basement adds usable square footage for storage or living space, but appraisers typically report it separately from above-grade square footage, since it sits below ground level even when heated and finished.
Can I estimate square footage using Google Maps
Yes, but the two Google tools do different jobs. Google Maps measures straight-line distance between points, so you can trace a lot's length and width and multiply them for a rough estimate.
For an actual enclosed area, Google Earth's measure tool is built for it: you place points around the perimeter, close the shape back at the starting point, and it reads the square footage or square meters directly.
Converting square feet to yards, meters and material cost
Carpet, sod and some vinyl flooring are priced by the square yard, not the square foot. Divide square feet by 9 to convert, since one square yard is 3 feet by 3 feet, or 9 square feet.
For metric, multiply square feet by 0.092903 to get square meters. A 200 square foot room is about 18.6 square meters, worth knowing if you are ordering tile or flooring from a metric supplier.
Diagonal or herringbone layouts typically add 10 to 15 percent to the material you buy, since angled cuts create more waste than a straight run.
For a concrete patio or slab priced the same way, the concrete slab calculator turns your square footage and thickness into cubic yards, bags and an estimated cost.
Frequently asked questions
How do I calculate sq feet?
How many sq ft is a 12x12 room?
How big is 10x10 in sq ft?
Can I estimate square footage using Google Maps?
How do I convert square feet to square yards?
Sources and references
These references and structured source records support the method and material data used on this page.
- Square foot (Wikipedia)
- Area (Wikipedia)
- Google Earth Help: Measure distances and areas
- Fannie Mae: Standardizing Property Measuring Guidelines (ANSI Z765)