Square Footage Calculator
Area 1
Sample shape, not to scale.
Area __n__
Sample shape, not to scale.
No result yet. Enter length and width.
Price
Optional. The cost is the sq ft figure, rounded up to 0.01, times your price.
How this is calculated
How to calculate square footage
Square footage is the area of a flat surface, counted in squares one foot on each side.
- Rectangle: length × width.
- Circle: π × (diameter ÷ 2)². Measure the diameter straight across the middle.
- Triangle: base × height ÷ 2, with the height taken at a right angle to the base.
- Ring: π × ((outer diameter ÷ 2)² − (inner diameter ÷ 2)²), the outer circle less the hole.
- Trapezoid: (base + top) ÷ 2 × height, where base and top are the two parallel sides and the height is the distance between them.
- Known area: for a figure you already have, from a plan or a survey, so the other calculators can use it.
Turn inches into a fraction of a foot before you multiply. 12 ft 6 in is 12.5 ft, not 12.6, because 6 in is half of a foot. The calculator does this for you when you fill in the inches box.
A space with a more complicated outline is the sum of simpler ones. Enter each piece as its own area and the result is the total.
Examples
Bedroom: 12 ft 6 in × 10 ft
- Area: 12 ft 6 in × 10 ft = 125 sq ft = 11.61 m²
125 sq ft. Square meters: 11.61 m². Square yards: 13.89 sq yd.
L-shaped lawn, as two rectangles: Area 1: 20 ft × 12 ft; Area 2: 8 ft × 6 ft
- Area 1: 20 ft × 12 ft = 240 sq ft = 22.30 m²
- Area 2: 8 ft × 6 ft = 48 sq ft = 4.46 m²
- Total area: 240 sq ft + 48 sq ft = 288 sq ft = 26.76 m²
288 sq ft 2 areas added. Square meters: 26.76 m². Square yards: 32.00 sq yd.
Round patio: 12 ft
- Area: π × (12 ft ÷ 2)² = 113.1 sq ft = 10.51 m²
113.1 sq ft. Square meters: 10.51 m². Square yards: 12.57 sq yd.
Bed with two parallel sides: Base 14 ft, top 10 ft, height 6 ft
- Area: (14 ft + 10 ft) ÷ 2 × 6 ft = 72 sq ft = 6.69 m²
72 sq ft. Square meters: 6.69 m². Square yards: 8.00 sq yd.
Square footage of common shapes
| Shape and size | Square feet | Square meters | Square yards |
|---|---|---|---|
| Rectangle: 10 ft × 10 ft | 100 sq ft | 9.29 m² | 11.11 sq yd |
| Rectangle: 12 ft × 12 ft | 144 sq ft | 13.38 m² | 16.00 sq yd |
| Rectangle: 20 ft × 15 ft | 300 sq ft | 27.87 m² | 33.33 sq yd |
| Circle: 10 ft | 78.5 sq ft | 7.30 m² | 8.73 sq yd |
| Circle: 16 ft | 201.1 sq ft | 18.68 m² | 22.34 sq yd |
| Triangle: 10 ft × 8 ft | 40 sq ft | 3.72 m² | 4.44 sq yd |
| Triangle: 12 ft × 9 ft | 54 sq ft | 5.02 m² | 6.00 sq yd |
| Ring: Outer diameter 8 ft, inner diameter 2 ft | 47.1 sq ft | 4.38 m² | 5.24 sq yd |
| Trapezoid: Base 14 ft, top 10 ft, height 6 ft | 72 sq ft | 6.69 m² | 8.00 sq yd |
Questions
How do I measure a space that isn't a rectangle?
Break it into rectangles, circles and triangles, then enter each piece with "Add another area". An L-shaped room is two rectangles. A corner cut off at an angle is a rectangle plus a triangle. The calculator shows the area of each piece and their sum.
Which measurement of a triangle is the height?
The height is the distance from the base to the opposite corner, measured at a right angle to the base. It is not the length of a sloping side. On a right-angled triangle the two sides that meet at the square corner are the base and the height.
How do I measure a ring or a trapezoid?
A ring, such as the bed around a tree trunk or a path around a round pond, takes two diameters measured straight across through the centre, the outer edge and the inner edge; its area is the outer circle less the inner one. A trapezoid has two parallel sides. Enter both, and the height as the distance between them measured at a right angle, not along a slanted side.
Why does the circle ask for the diameter?
The diameter is what a tape gives you directly, stretched straight across the widest part. The calculator halves it to get the radius. If you only have the radius, double it.
What are square yards used for?
Carpet and sod are often priced by the square yard. One square yard is 3 ft by 3 ft, which is 9 sq ft, so the square-yard line is the square footage divided by 9.
Does the result include extra for cuts and offcuts?
No. It is the measured area and nothing more. How much extra flooring, tile or sod to buy depends on the product and the layout, and this site has no sourced figure for it, so none is added. Check what the maker of your product advises.
I need a depth of material over this area. What next?
Area times depth is a volume. The mulch, topsoil, gravel and concrete calculators take the same length and width plus a depth and give the amount to buy, so you do not need to carry the square footage across by hand.
Can it work out the cost?
Yes. Enter a price per square foot under Price, such as the shelf price of flooring or sod. The square footage is rounded up to the next 0.01 sq ft and multiplied by your price. Waste and offcuts are not added, so allow for them yourself.
Related tools
Sources
Area formulas are plain geometry and are not taken from any publisher. The only reference values on this page are unit definitions. One foot is exactly 0.3048 m, which fixes the square-meter figure, and a yard is three feet, which makes a square yard 9 sq ft.
- NIST Handbook 44 (2024), Appendix C, General Tables of Units of Measurement, accessed October 8, 2026
- NIST Special Publication 811, Appendix B.9, conversion factors listed by kind of quantity, accessed October 8, 2026
Last reviewed: October 8, 2026