One tool for both meanings of “square”: square footage from length × width (rooms, flooring, land) and the square of a number x² with step-by-step work. Free, private, no sign-up.
Enter the length and width of any rectangle. Works for rooms, yards, walls, land — in feet, inches, or metric.
ft + optional inches (e.g. 10 ft 6 in)
ft + optional inches
Enter any number — integer, decimal, or negative. Shows the multiplication step-by-step, the inverse square root, and whether it is a perfect square.
⚠️ Negative numbers: (−4)² = 16 but −4² = −(4×4) = −16. Parentheses decide. This calculator squares the value you type, including its sign.
Add every room (or every rectangle of an L-shaped room). The total is what flooring, carpet, and paint estimators actually need.
| Room / section | Length (ft) | Width (ft) | Area (ft²) | |
|---|---|---|---|---|
| TOTAL | 0 | |||
From a known area, estimate tiles (or flooring planks) including cutting waste, and how many boxes to buy. Defaults to the industry-standard 10% waste allowance.
Convert any square area unit to any other — square feet to square meters, square yards to square feet, acres, square inches, hectares and more.
| 1 square foot equals | Value |
|---|---|
| Square inches | 144 in² |
| Square yards | 0.111111 yd² |
| Square meters | 0.09290304 m² |
| Square centimeters | 929.0304 cm² |
| Acres | 0.0000229568 ac |
| Hectares | 0.0000092903 ha |
Exact definitions: 1 ft = 0.3048 m (international foot), so 1 ft² = 0.09290304 m² exactly; 1 acre = 43,560 ft² exactly.
Every integer square from 1² to 30² — handy for homework checks and mental-math practice.
| x | x² | x | x² | x | x² |
|---|---|---|---|---|---|
| 1 | 1 | 11 | 121 | 21 | 441 |
| 2 | 4 | 12 | 144 | 22 | 484 |
| 3 | 9 | 13 | 169 | 23 | 529 |
| 4 | 16 | 14 | 196 | 24 | 576 |
| 5 | 25 | 15 | 225 | 25 | 625 |
| 6 | 36 | 16 | 256 | 26 | 676 |
| 7 | 49 | 17 | 289 | 27 | 729 |
| 8 | 64 | 18 | 324 | 28 | 784 |
| 9 | 81 | 19 | 361 | 29 | 841 |
| 10 | 100 | 20 | 400 | 30 | 900 |
Area of a rectangle = length × width. All lengths are first converted to feet (inches ÷ 12, yards × 3, meters ÷ 0.3048, centimeters ÷ 30.48), then multiplied. The result in square feet is exact to floating-point precision; displayed values are rounded for readability while the full value drives conversions. Square feet vs. square meters: 1 ft² = 0.09290304 m² exactly, by the international definition of the foot (0.3048 m).
When you enter 10 ft 6 in, the calculator uses 10 + 6/12 = 10.5 ft. This is the standard contractor method — never multiply feet by inches directly.
x² = x × x, computed with standard IEEE-754 double precision. Negative inputs are squared with their sign, i.e. (−4)² = 16. The inverse operation shown is the principal (non-negative) square root √x. A perfect square is an integer that is the square of another integer (1, 4, 9, 16, 25, …); the checker tests √n rounded back.
Tiles needed = ceil(area ÷ tile area × (1 + waste%)). Boxes = ceil(tiles ÷ tiles per box). Rounding always goes up — you cannot buy a fraction of a tile. The 10% default waste allowance is the flooring-industry standard for straight-lay patterns; diagonal or herringbone layouts need 15%.
For L-shaped or irregular rooms, split the floor plan into rectangles, measure each, and add the areas — that is exactly what the Multi-Room tab does. Overlapping sections must be counted only once.
Multiply length by width, both measured in feet: square feet = length (ft) × width (ft). For example, a room 12 ft long and 10 ft wide is 12 × 10 = 120 square feet. If your measurements are in inches, divide each by 12 first, or use the feet-and-inches inputs in the calculator above.
A 12 ft × 10 ft room is 120 square feet (12 × 10 = 120). In metric that is 120 × 0.09290304 = 11.15 square meters, and in square yards it is 120 ÷ 9 = 13.33 square yards.
Convert the inches to a fraction of a foot first: inches ÷ 12. For example, 10 ft 6 in becomes 10 + 6/12 = 10.5 ft. Then multiply: a room 10 ft 6 in × 12 ft is 10.5 × 12 = 126 square feet.
Feet measure length (one dimension); square feet measure area (two dimensions). A 10 ft board is 10 feet long, but a 10 ft × 10 ft floor covers 100 square feet. You cannot compare them directly — area needs both length and width.
120 square feet × 0.09290304 = 11.148 square meters. The conversion factor is exact: one foot is defined as 0.3048 meters, so one square foot is 0.3048² = 0.09290304 square meters. To go the other way, multiply square meters by 10.7639.
One acre is exactly 43,560 square feet — about 208.7 ft × 208.7 ft. A standard American football field (without end zones) is roughly 1.1 acres. Use the unit converter above to convert acres to square meters (1 acre = 4,046.86 m²) or hectares.
Multiply the number by itself: x² = x × x. For example, 5² = 5 × 5 = 25, and 2.5² = 2.5 × 2.5 = 6.25. The name comes from geometry: the area of a square with side x is x × x, hence “x squared.”
(−4)² means (−4) × (−4) = 16, because a negative times a negative is positive. Written as −4² without parentheses, convention reads it as −(4 × 4) = −16. Parentheses decide the meaning, so always write (−4)² when you want to square a negative number. This calculator squares the full value you type, including its sign.
A perfect square is an integer that equals another integer squared: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, and so on. The Square-a-Number tab above tells you whether your result is a perfect square and shows its square root.
Buy 10% extra for straight-lay tile or plank flooring — the industry standard allowance for cuts and breakage. For diagonal, herringbone, or rooms with many corners, allow 15%. The Material Estimator tab applies your chosen waste percentage and rounds up to whole tiles and whole boxes.
Split the floor plan into rectangles, measure the length and width of each, calculate each area, and add them together — counting any overlap only once. The Multi-Room tab is built for exactly this: add one row per rectangle and it totals everything automatically.
Divide by 9: 120 ÷ 9 = 13.33 square yards. One square yard is 3 ft × 3 ft = 9 ft². Carpet is often priced per square yard, so converting helps compare quotes.
Divide by 144, because 1 ft² = 12 in × 12 in = 144 in². For example, 500 square inches ÷ 144 = 3.47 square feet.
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