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Pick a shape, enter sizes in feet and inches, metres or any mix, and see square feet, square metres and total cost instantly.
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A square footage calculator finds the area of a space in square feet. For a rectangle it multiplies length by width, so a room 12 ft by 15 ft is 180 sq ft. For other shapes it applies the matching formula, then converts the result to square yards, square metres or a total cost.
This square feet calculator covers nine shapes, from plain rooms to rings, triangles and pie-slice sectors, and every measurement can use its own unit. Type 12 ft 6 in, 3.8 m or 6 1/2 in and the sq ft calculator converts everything before it works out the area, so it also works as a general area calculator. For other everyday maths, see the full list of free calculators.
| Size | Sq ft | Sq yd | Sq m | Typical use |
|---|---|---|---|---|
| 10 × 10 ft | 100 | 11.11 | 9.29 | Small bedroom or home office |
| 10 × 12 ft | 120 | 13.33 | 11.15 | Bedroom |
| 12 × 12 ft | 144 | 16 | 13.38 | Bedroom or kitchen |
| 12 × 14 ft | 168 | 18.67 | 15.61 | Main bedroom |
| 12 × 16 ft | 192 | 21.33 | 17.84 | Living room |
| 14 × 16 ft | 224 | 24.89 | 20.81 | Large living room |
| 16 × 20 ft | 320 | 35.56 | 29.73 | Open-plan living area |
| 20 × 20 ft | 400 | 44.44 | 37.16 | Two-car garage (small) |
| 24 × 24 ft | 576 | 64 | 53.51 | Two-car garage |
| 30 × 40 ft | 1,200 | 133.33 | 111.48 | Small house footprint |
Four steps. The answer updates while you type, with no Calculate button.
Choose a rectangle for most rooms, a border for a path around a lawn or pool, a ring for a circular edge, or a triangle, trapezoid, sector or parallelogram for odd corners.
Type each size and pick its unit: feet, feet and inches, inches, yards, miles, metres, kilometres, centimetres or millimetres. Fractions like 6 1/2 are fine.
Set how many identical areas you have, add a waste allowance for cuts, and enter a price per square foot, yard or metre to get the total cost.
Open the working to see each step, copy the result, share a link that reopens the same numbers, or add each room to the project list for a running total.
Measure in feet and these formulas give square feet. The examples match the calculator defaults, so you can check them against the tool.
| Shape | Formula | Example | Area |
|---|---|---|---|
| Rectangle or square | length × width | 30 × 20 ft | 600 sq ft |
| Rectangle border | L × W − (L − 2b) × (W − 2b) | 30 × 20 ft, border 2 ft | 184 sq ft |
| Circle | π × d² ÷ 4 (or π × r²) | diameter 30 ft | 706.86 sq ft |
| Ring (annulus) | π ÷ 4 × (D² − d²) | outer 30 ft, width 2 ft | 175.93 sq ft |
| Triangle, three sides | √(s(s − a)(s − b)(s − c)), s = (a + b + c) ÷ 2 | 30, 45 and 50 ft | 666.59 sq ft |
| Triangle, base and height | base × height ÷ 2 | base 30, height 20 ft | 300 sq ft |
| Trapezoid | (a + b) ÷ 2 × height | 30 and 45 ft, height 20 ft | 750 sq ft |
| Sector (pie slice) | θ ÷ 360 × π × r² | radius 30 ft, 90° | 706.86 sq ft |
| Parallelogram | base × height | base 30, height 20 ft | 600 sq ft |
| Unit | Equals | Also | Metric |
|---|---|---|---|
| 1 square foot | 144 sq in | 0.111111 sq yd | 0.09290304 sq m |
| 1 square yard | 9 sq ft | 1,296 sq in | 0.8361274 sq m |
| 1 square metre | 10.7639 sq ft | 1.196 sq yd | 10,000 sq cm |
| 1 acre | 43,560 sq ft | 4,840 sq yd | 4,046.86 sq m |
| 1 hectare | 107,639.1 sq ft | 2.4711 acres | 10,000 sq m |
| 1 square mile | 27,878,400 sq ft | 640 acres | 2.59 sq km |
Most square footage tools handle one rectangle in one unit. This is what changes here.
| Feature | This calculator | Typical calculator |
|---|---|---|
| Shapes | 9, including border, ring, sector and triangle from three sides | Rectangle only, or 4 to 7 shapes |
| Units | A separate unit for every measurement, metric and imperial mixed | One unit for the whole calculation |
| Feet and inches | Feet and inches boxes, plus fractions such as 6 1/2 | Decimal feet only |
| Speed | Instant result as you type | Press Calculate and wait for a reload |
| Working | Every step with your numbers, including unit conversion | Answer only |
| Waste allowance | Built in, with one-tap 10 and 15 percent | Left to you |
| Several rooms | Project list with total area and total cost | One area at a time |
| Cost | Price per sq ft, sq yd, sq m, sq in or sq cm, in 5 currencies | Price per sq ft only, if at all |
| Sharing | Link that reopens the exact inputs | None |
Measure each room, add a waste allowance, and enter the price per square foot or square yard to see what the material costs before you order.
Measure the floor as rectangles and leave out areas under fixed cabinets or a tub that will not be tiled. Patterned and diagonal layouts usually need a larger waste figure.
Treat each wall as a rectangle: room perimeter times ceiling height. A 12 by 14 ft room with 8 ft walls has about 52 × 8 = 416 sq ft of wall before doors and windows.
Use the border shape for a path around a pool or garden bed, the ring for a circular edge, and a sector for a curved corner bed.
Compare listings by price per square foot. For a whole project, track each item and its cost with the expense calculator.
Check area answers for triangles, trapezoids and circles, and read the working to see how Heron formula and the sector formula are applied.
Measure wall to wall at floor level with a tape, to the nearest inch. Split L-shaped or irregular rooms into rectangles: a 16 by 12 ft room with an 8 by 6 ft alcove is 192 + 48 = 240 sq ft. Jot the sizes down as you go in the online notepad so nothing gets lost between rooms.
Feet measure length; square feet measure area. A 10 ft square is 100 sq ft, and doubling both sides gives four times the area.
Multiplying feet by metres gives nonsense. The calculator converts each measurement first, so mixed units are safe here.
6 inches is 0.5 ft, not 0.6 ft. Typing 12.6 for 12 ft 6 in overstates a 10 ft wide room by a full square foot.
For triangles, trapezoids and parallelograms the height is measured straight across at a right angle, not along a sloping side.
Keep full precision while you calculate and round only the final number. The significant figures calculator helps when you report a measured value.
Flooring and tile come in cartons that cover a fixed area. Divide the area to buy by the coverage per box and round up.
Listings and appraisals in the United States often follow the ANSI Z765 standard, which measures finished area from the outside of the walls. A sum of room sizes is usually smaller.
Free-form shapes need to be split into the nine shapes here. The more pieces you use, the closer the total gets to the real area.
The maths is exact, but a measurement off by an inch on each side of a 12 ft room changes the area by about 2 sq ft. Measure twice before you buy.
The unit definitions and formulas on this page come from these references. The calculator was checked against nine reference results, one for each shape.
Short answers to the questions people ask most.
Multiply the length by the width, with both measured in feet. A room 12 ft long and 15 ft wide is 12 × 15 = 180 square feet. For other shapes use the matching formula, or split the space into rectangles and add them up.
A 12 by 12 foot room is 144 square feet, which is about 13.38 square metres or 16 square yards.
Turn the inches into a decimal foot by dividing by 12, so 12 ft 6 in becomes 12.5 ft, then multiply as usual. In this calculator you can pick ft + in as the unit and type feet and inches in separate boxes, and fractions such as 6 1/2 work too.
Multiply square feet by 0.09290304, the exact factor that follows from 1 foot = 0.3048 metre. For example, 500 sq ft is about 46.45 sq m. To go the other way, multiply square metres by about 10.764.
One acre is 43,560 square feet. A square plot of one acre measures about 208.7 feet on each side.
Split the room into two rectangles, find the area of each, and add them. A 16 by 12 ft section plus an 8 by 6 ft alcove is 192 + 48 = 240 sq ft. Use Add to list for each part and the project list shows the total.
Multiply pi by the diameter squared and divide by 4, which is the same as pi times the radius squared. A circle 10 ft across is about 78.54 square feet.
Many flooring guides suggest adding roughly 5 to 15 percent for cuts and mistakes, with more for diagonal layouts and patterned tile. Check the instructions for your product, then type the percentage in the waste allowance box.
Multiply the area by the price per square foot. For example, 240 sq ft at 4.50 per sq ft costs 1,080. If your price is per square yard or square metre, choose that unit and the calculator converts the area for you.
Usually not. Formal home measurements, such as the ANSI Z765 standard used in the United States, measure finished area from the outside of the walls and have rules for stairs and low ceilings, so they differ from a sum of room sizes.
No. The calculation runs in your browser and nothing is sent to a server. Your project list and currency choice are saved on your own device only, and you can clear the list at any time.