Square Footage Calculator
Room area for flooring, paint and materials.
Reviewed by the Calculation Machine team · Updated 24 October 2026 · How we check our maths
Your values
ⓘ Live results
- Area
- 216 sq ft
- With waste allowance
- 237.6 sq ft
- In square metres
- 20.07
- Material cost
- $831.6
- Perimeter
- 60 ft
Quick answer
Square footage is the area of a space: length × width, with both measured in feet. A room 12 ft long and 11 ft wide is 12 × 11 = 132 sq ft. For flooring, add a waste allowance – 10% brings that room to 145.2 sq ft. To convert to square meters, divide square feet by 10.764.
What the Square Footage calculator does
This calculator works out the floor area of a rectangular room or space, the area with a cutting and waste allowance added, the same area in square meters, the perimeter (useful for baseboard and trim) and the material cost at a price per square foot.
Use it to order flooring, tile, carpet, underlay, sod or paint primer, or to compare quotes priced per square foot. For L-shaped and irregular rooms, split the floor into rectangles, run each one, and add the results.
Material-specific tools go a step further: the flooring calculator rounds to whole boxes, the tile calculator counts tiles and grout, and the paint calculator uses wall area rather than floor area.
The formula
Area = L × W Area with waste = L × W × (1 + waste ÷ 100) Perimeter = 2 × (L + W) Cost = area with waste × price per sq ft Square meters = sq ft ÷ 10.764
| Symbol | Meaning | Unit |
|---|---|---|
| L | Length of the room or area | ft |
| W | Width of the room or area | ft |
| waste | Extra material for cuts, breakage and pattern matching | % |
| price | Material price per square foot (enter 0 to skip cost) | $/sq ft |
Area of a rectangle is basic Euclidean geometry. The conversion factor 10.7639 sq ft per square meter comes from the international foot (exactly 0.3048 m). Real estate listings measure finished square footage differently – in the US, the ANSI Z765 standard measures to exterior walls and excludes garages and some low-ceiling space – so a floor-plan total will not match a listing exactly.
Worked examples
Bedroom flooring
A 12 × 11 ft bedroom getting laminate at $4.25 per sq ft, with 10% waste.
Inputs
- Length12 ft
- Width11 ft
- Waste allowance10 %
- Material price4.25 $/sq ft
Result
- Area132 sq ft
- With waste allowance145.2 sq ft
- In square metres12.26
- Material cost$617.1
- Perimeter46 ft
Buy for about 145 sq ft, roughly $617 of laminate. Round up to whole boxes, and add underlay for the same area.
Living room with diagonal tile
A 24 × 15.5 ft open living area laid with tile on the diagonal at $7 per sq ft.
Inputs
- Length24 ft
- Width15.5 ft
- Waste allowance15 %
- Material price7 $/sq ft
Result
- Area372 sq ft
- With waste allowance427.8 sq ft
- In square metres34.56
- Material cost$2994.6
- Perimeter79 ft
Diagonal layouts waste more at the edges, so the 15% allowance takes 372 sq ft up to about 428 sq ft and roughly $2,995 in tile.
Small bathroom, area only
An 8 × 5 ft bathroom floor, measured to compare contractor quotes.
Inputs
- Length8 ft
- Width5 ft
- Waste allowance0 %
- Material price0 $/sq ft
Result
- Area40 sq ft
- With waste allowance40 sq ft
- In square metres3.72
- Material cost$0
- Perimeter26 ft
40 sq ft (3.72 m²) with a 26 ft perimeter. Divide each quote by 40 to compare price per square foot, but expect small rooms to cost more per foot because of setup and cutting time.
Waste allowance by material
The right allowance depends on the material and the layout. Rooms with many corners, closets or doorways need the upper end of each range.
| Material and layout | Typical allowance |
|---|---|
| Sheet vinyl, simple room | 5–10% |
| Laminate or vinyl plank, straight lay | 5–10% |
| Hardwood, straight lay | 7–10% |
| Tile, straight grid | 10% |
| Tile or plank, diagonal or herringbone | 15–20% |
| Carpet (from 12 ft rolls) | 10–15%, more if seams must run one way |
Measuring irregular rooms
- L-shaped rooms: split into two rectangles that do not overlap, calculate each, and add them.
- Bay windows and alcoves: measure the alcove as its own rectangle; for an angled bay, a triangle's area is ½ × base × height.
- Circles: area = 3.1416 × radius². A round rug area 8 ft across is about 50 sq ft.
- Feet and inches: convert inches to decimal feet before entering – 11 ft 6 in is 11.5 ft, 9 in is 0.75 ft.
- Metric: if you measured in meters, multiply each side by 3.281 to get feet, or multiply the area in m² by 10.764.
Floor area versus home square footage
Adding up room areas gives net floor area, which is smaller than the gross square footage in a listing because walls, stairs and hallways are excluded or counted differently. Use room-by-room totals for ordering materials, and the official listing figure when comparing home prices with the price per square foot calculator.
How to use the Square Footage Calculator
- 1Measure the longest length and width of the room at floor level, wall to wall, in feet.
- 2Enter both figures; convert inches to decimals first (6 in = 0.5 ft).
- 3Set a waste allowance for your material, or 0 if you only need the area.
- 4Enter the price per square foot to see material cost, then round up to whole boxes or rolls when buying.
Frequently asked questions
How do I calculate square footage of a room?
Multiply the length by the width in feet. A 15 × 12 ft room is 180 sq ft.
How do I calculate square feet from inches?
Multiply length by width in inches, then divide by 144, the number of square inches in a square foot. A 60 × 48 in area is 2,880 ÷ 144 = 20 sq ft.
How many square feet is a 10×12 room?
120 sq ft, or about 11.1 m². With a 10% flooring allowance, buy 132 sq ft.
How do I convert square feet to square yards?
Divide by 9, since a square yard is 3 ft × 3 ft. 216 sq ft is 24 sq yd – the unit carpet is sometimes priced in.
Should I measure under kitchen cabinets and fixed furniture?
For flooring, usually not – measure only the exposed floor, unless the new floor must run under appliances such as a dishwasher. For heating or listing area, measure the full room.
References
- ANSI Z765 – Square Footage: Method for Calculating — American National Standards Institute / Home Innovation Research Labs
- Guide for the Use of the International System of Units (SI), Special Publication 811 — National Institute of Standards and Technology
About this calculator
- Built and reviewed by the Calculation Machine team · How we build and test calculators
- Last reviewed: October 24, 2026
- Report an error