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Square footage calculator

Measure each part of the space, pick its shape and enter the sizes in feet and inches or meters. Add rooms together for a total, take away areas you won't cover, and enter a price per square foot to see the cost.

Units
  1. Area 1120 sq ft
    This area

Buying flooring, tile, sod or paint? (optional)

Add extra for cuts and see what to buy and what it costs.

Extra for waste
Total area
120 sq ft
12 ft × 10 ft

Same area in other units

Square yards
13.33
Square meters
11.15
Acres
0.0028
  • Nothing is uploaded
  • Free, no sign-up
  • Works on phone and desktop

How to calculate square footage

  1. 1

    Pick a shape for the first area: rectangle, L-shape, circle, triangle or trapezoid. The little drawing shows what each letter means.

  2. 2

    Type the sizes the way you read a tape measure: 12' 6", 12 ft 6 in and 12.5 all work. Switch to metric for meters and centimeters.

  3. 3

    Use Add an area for more rooms, and Leave out an area for what you won't cover, such as a kitchen island or a fireplace hearth.

  4. 4

    Read the total in square feet, with square yards, square meters and acres below. Add a waste allowance and a price to see what to buy and what it costs.

Features

  • Six shapes

    Rectangles, L-shapes, circles, trapezoids, and triangles by base and height or by their three sides, for corners of a lot.

  • Add and subtract

    Build a whole floor from up to 20 areas, then take out islands, tubs and built-ins that don't get flooring.

  • Tape-measure input

    Mix feet, inches and fractions such as 10' 9 1/2", or work in meters. Every field shows how it read your entry.

  • What to buy and cost

    Add 5 to 15% for waste, round up to whole boxes or rolls, and multiply by the price per square foot.

Area formulas for each shape

Every shape comes down to a simple formula. Measure in feet (or convert inches to feet by dividing by 12) and the answer is in square feet. The examples below are worked out with the same math as the calculator.

ShapeFormulaExample
Rectangle or squarelength × width12 × 14 ft = 168 sq ft
L-shapetwo rectangles, added12 × 10 + 6 × 4 ft = 144 sq ft
Circleπ × radius²10 ft across = 78.54 sq ft
Trianglebase × height ÷ 210 ft base, 6 ft high = 30 sq ft
Triangle by sidesHeron's formula30, 40 and 50 ft sides = 600 sq ft
Trapezoid(side A + side B) ÷ 2 × height8 and 12 ft sides, 5 ft apart = 50 sq ft

A triangle's height is measured square to the base, not along a sloping side. If that's hard to measure, as it often is on a lot line, measure all three sides instead and pick Triangle by sides.

Worked example: flooring for an open-plan floor

Say you're putting new flooring through a living room of 15 × 18 ft (270 sq ft), an L-shaped kitchen made of a 12 × 10 ft part and a 6 × 4 ft part (144 sq ft), and a hallway 3 ft 6 in wide and 12 ft long (42 sq ft). The kitchen island, 3 × 6 ft, stays where it is, so you leave out its 18 sq ft.

  • Area to cover: 270 + 144 + 42 − 18 = 438 square feet (48.67 square yards).
  • With 10% for waste: 481.8 square feet.
  • In boxes of 20 sq ft: 25 boxes, covering 500 square feet.
  • At $3.50 a square foot: $1,750.00 for the flooring itself.

For a single 12 × 14 ft bedroom the same steps give 168 square feet, 184.8 with 10% extra, or about $646.80 at $3.50 a square foot.

How to measure a room

  • Measure wall to wall at floor level, and round up to the next inch. Walls are rarely perfectly square, so measure both ends of a long room and use the larger figure.
  • Include closets and alcoves that get the same flooring as separate areas, and leave out anything fixed in place, such as cabinets, islands and tubs.
  • Split odd shapes into rectangles and triangles. A room with an angled corner is a rectangle minus a triangle.
  • For walls rather than floors, multiply the length around the room by the ceiling height. The drywall calculator does this and takes off doors and windows.

Square feet in other units

UnitIn square feet
1 square yard9
1 square meter10.764
1 acre43,560
1 hectare107,639

From area to materials

Square footage is the starting point for most home projects. Paint cans usually list a coverage per gallon per coat, often somewhere around 250 to 400 square feet, so check the label for your paint. Sod, tile and flooring are sold by the square foot or by the box, pallet or roll, so enter the coverage per box to round up to whole units.

Anything with depth is a volume, not an area. For a patio or slab, take the square footage to the concrete calculator; for paths and driveways use the gravel calculator, and for beds the mulch calculator. Sizing an air conditioner for the room you just measured? The BTU calculator starts from the same floor area.

Frequently asked questions

How do I calculate square footage?

Measure the length and width in feet and multiply them. A room 12 ft by 14 ft is 168 square feet. If a measurement has inches, divide the inches by 12 first: 12 ft 6 in is 12.5 ft, so a 12' 6" × 10' 9" room is 134.4 square feet.

How do I find the square footage of an L-shaped room?

Split it into two rectangles that don't overlap, work out each one and add them. An L made of a 12 × 10 ft part and a 6 × 4 ft part is 120 + 24 = 144 square feet. Choose L-shape in the calculator and it does the split for you.

How many square feet are in a square yard, a square meter and an acre?

A square yard is 9 square feet (3 ft × 3 ft). A square meter is about 10.76 square feet. An acre is 43,560 square feet, or 4,840 square yards. Carpet is often priced by the square yard, so divide square feet by 9 to compare.

How much extra flooring should I buy?

Most installers add about 5 to 10% for straight layouts of plank, laminate or tile, and 15% or more for diagonal or herringbone patterns and rooms with lots of corners. The flooring maker's instructions may give their own figure. Keep a spare box for future repairs.

Does the square footage of a house include the garage?

Usually not. US appraisers commonly follow the ANSI Z765 standard, which counts finished, above-grade living space measured from the outside of the exterior walls. Garages, unfinished spaces and basements are reported separately. For flooring or paint, measure each room from the inside instead.

How do I work out the area of a circle?

Measure across the widest point to get the diameter, halve it for the radius, then multiply π (3.1416) × radius × radius. A round patio 10 ft across has a 5 ft radius, so it covers 3.1416 × 5 × 5 = 78.54 square feet.

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