Square Footage Calculator
Find the area of a rectangle, circle, triangle, trapezoid or rectangular border in square feet, square metres, square yards, square inches and acres. Add a waste allowance, repeat the shape with a quantity, then turn on the cost estimate to price the material per square foot or square metre.
Formula
Worked example
A 12 ft × 10 ft room is 120 ft² net. Add 10% waste and you buy for 132 ft² (about 12.3 m², or 14.7 yd²). At $4 per ft² that is roughly $528 of material.
How the calculation works
Pick a shape and the calculator uses the matching area formula. A rectangle or square is length times width. A circle is pi times the radius squared, where the radius is half the diameter you enter. A triangle is half the base times its perpendicular height. A trapezoid is half the sum of its two parallel sides times the height between them. A rectangular border, such as a path around a patio, is the outer rectangle minus the inner rectangle left after taking the border width off each edge. Every dimension can be entered in feet, inches, metres, centimetres or yards, and each is converted to feet before the area is worked out.
Quantity, waste and the units you get back
Set the number of areas to repeat an identical shape, for example five identical rooms or several stair treads, and the net area is multiplied by that count. The waste allowance then adds a percentage on top for cuts, offcuts and pattern matching; ten to fifteen percent is typical for flooring and tile, and large format or diagonal layouts often need more. The result is shown both as the net area and as the area to buy, and converted into square metres, square yards, square inches and acres at the same time so you can match whatever unit your supplier quotes in.
Estimating material cost
Turn on the cost estimate, choose your currency, and enter the material price together with whether it is quoted per square foot, per square metre or per square yard. The calculator bills the area to buy (waste included) at that price to give a planning figure for the material alone, before delivery, underlay, adhesive or labour. Because flooring and tile are sold in fixed box or pallet sizes, treat the figure as a starting point and round your order up to whole boxes once you know the coverage per pack.
Limitations and irregular spaces
Each calculation covers one shape. For an L-shaped, T-shaped or otherwise irregular room, split the floor plan into the rectangles, triangles and trapezoids that make it up, calculate each one, and add the areas together. Subtract large fixtures you will not cover, such as a kitchen island or a stair opening. Measure to the longest points of each wall, including alcoves and bay windows you intend to floor, since accurate measurement is by far the biggest source of error in any square footage estimate.
Area conversions and shape formulas
| Item | Value or formula | Notes |
|---|---|---|
| 1 m² | 10.764 ft² | Multiply ft² by 0.0929 to get m² |
| 1 yd² | 9 ft² | Divide ft² by 9 to get yd² |
| 1 acre | 43,560 ft² | Common for land and lots |
| Rectangle | L × W | Square is a rectangle with equal sides |
| Circle | π × r² | Radius = diameter ÷ 2 |
| Triangle | ½ × base × height | Height is perpendicular to the base |
| Trapezoid | ½ × (a + b) × h | a and b are the parallel sides |
How the units relate, plus the formula used for each shape.
Frequently asked questions
How do I calculate square footage from feet and inches?
Convert inches to a decimal fraction of a foot by dividing by 12, then add that to the whole feet before multiplying length by width. For example, 12 feet 6 inches is 12.5 feet. You can also just enter each dimension in inches here and the calculator converts it for you.
How many square feet are in a square metre?
One square metre is about 10.764 square feet, and one square foot is about 0.0929 square metres. This calculator shows your area in square feet, square metres, square yards, square inches and acres at once, so you can match whatever unit a quote or product is given in.
How much flooring do I need for a 12x12 room?
A 12 foot by 12 foot room is 144 square feet of floor area. With the standard 10 percent waste allowance for cuts and pattern matching, plan to buy around 158 to 160 square feet. Confirm coverage with your specific product, since large format tiles or diagonal layouts can need more.
How do I find the square footage of a circle or triangle?
For a circle, the area is pi times the radius squared, and the radius is half the diameter. For a triangle, it is half the base times the perpendicular height. Choose the matching shape above and enter the dimensions, and the calculator applies the right formula automatically.
How do I work out the cost of flooring per square foot?
Multiply the square footage you need to buy, including the waste allowance, by the price per square foot. Turn on the cost estimate to do this automatically; you can also enter a price per square metre or square yard if that is how your material is sold.