Area is length × width for a rectangle; every other room shape is a few rectangles, triangles or circles added together. Measure in whatever unit your tape shows: the calculator gives square feet when you measured in feet, inches or yards, and square meters when you measured in meters or centimeters, and shows the other units underneath.
Example: an L-shaped living room, 16 × 12 ft with a 6 × 6 ft dining nook. 16 × 12 = 192 ft², 6 × 6 = 36 ft², total 228 ft² (21.18 m²). With flooring at $4.25 per ft², that is $969 before the extra for cuts.
The formulas
| Shape | Area | Enter |
|---|---|---|
| Rectangle or square | length × width | A, B |
| L-shape | A × B + C × D (two rectangles that do not overlap) | A, B, C, D |
| Triangle | base × height ÷ 2 | base and the height from it to the opposite corner |
| Circle | π × (diameter ÷ 2)² | the diameter |
| Trapezoid | (side A + side B) ÷ 2 × the distance between them | the two parallel sides and the distance |
For a room with a bay window, a chimney breast or a cut corner, add or take away the small pieces. Most rooms are rectangles within an inch or two; measure each wall once at floor level and use the longer of the two opposite walls.
Common room sizes
| Room | ft² | m² |
|---|---|---|
| 10 × 10 ft | 100 | 9.29 |
| 10 × 12 ft | 120 | 11.15 |
| 12 × 12 ft | 144 | 13.38 |
| 12 × 15 ft | 180 | 16.72 |
| 14 × 16 ft | 224 | 20.81 |
| 20 × 20 ft (two-car garage) | 400 | 37.16 |
| 3 × 4 m | 129.17 | 12 |
| 4 × 5 m | 215.28 | 20 |
| 5 × 6 m | 322.92 | 30 |
Price per square foot and per square meter
Flooring, tiles and rent are quoted per square foot in the US and per square meter almost everywhere else. To compare, multiply a price per ft² by 10.7639, or divide a price per m² by it:
| Per ft² | Per m² |
|---|---|
| 1.00 | 10.76 |
| 2.50 | 26.91 |
| 4.00 | 43.06 |
| 6.00 | 64.58 |
| 10.00 | 107.64 |
The currency does not matter for the conversion. Pick yours in the calculator and enter the price for the unit you measured in.
Square feet, square yards and acres
Carpet in the US is often sold by the square yard (9 ft²), and land by the acre (43,560 ft², 4,046.86 m²). The results list both. For land, the acres to square meters converter also shows hectares and square miles. To cover the area you found, the tile calculator and the paint calculator take it from here.
Measuring a house you are viewing, with no signal? Once zet4u is saved on your phone, the calculator works offline.
Frequently asked questions
How do I calculate the square footage of a room?
Multiply the length by the width, both in feet: a 12 × 15 ft room is 180 ft². If you measured in feet and inches, turn the inches into a decimal first (12 ft 6 in = 12.5 ft), or enter inches directly and the calculator converts.
How many square feet are in a square meter?
10.7639. One square foot is exactly 0.09290304 m², because a foot is exactly 0.3048 m. Quick mental check: m² × 10 plus 8% gives ft²; ft² ÷ 10 minus 7% gives m².
How do I measure an L-shaped room?
Split it into two rectangles that do not overlap, measure each, and add them. Choose "L-shape" above and enter both. A room that is 16 × 12 ft with a 6 × 6 ft alcove is 192 + 36 = 228 ft².
How do I convert a price per square foot to a price per square meter?
Multiply by 10.7639: $3.50 per ft² is $37.67 per m². Going the other way, divide by 10.7639: €40 per m² is €3.72 per ft². The calculator gives the total cost for the unit you measured in.
Sources
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