Calculator + chartEnter your measurements below and it works the answer out.
Square footage is length × width. Enter your room in whatever units you measured in and this gives you the area in square feet, square meters and square yards, plus the flooring it takes.
| Room | Square feet | Square meters | Flooring to buy |
|---|---|---|---|
| 8 × 10 ft | 80 sq ft | 7.4 sq m | 88 sq ft |
| 10 × 10 ft | 100 sq ft | 9.3 sq m | 110 sq ft |
| 10 × 12 ft | 120 sq ft | 11.1 sq m | 132 sq ft |
| 12 × 12 ft | 144 sq ft | 13.4 sq m | 159 sq ft |
| 12 × 14 ft | 168 sq ft | 15.6 sq m | 185 sq ft |
| 12 × 16 ft | 192 sq ft | 17.8 sq m | 212 sq ft |
| 14 × 16 ft | 224 sq ft | 20.8 sq m | 247 sq ft |
| 15 × 20 ft | 300 sq ft | 27.9 sq m | 330 sq ft |
| 20 × 20 ft | 400 sq ft | 37.2 sq m | 440 sq ft |
| 20 × 30 ft | 600 sq ft | 55.7 sq m | 660 sq ft |
The flooring column is the area plus the standard 10% waste allowance, rounded up to the whole square foot.
The formula. Square footage is length × width, with both measurements in feet. A room 14 ft by 12 ft is 168 square feet. Everything else on this page is that one line plus a unit conversion.
Measuring in something other than feet. Convert every measurement to feet first, then multiply — never multiply mixed units. Inches ÷ 12, yards × 3, meters × 3.2808, centimeters ÷ 30.48. The common slip is 12 ft 6 in: that is 12.5 ft, not 12.6, because inches are twelfths. The calculator does the conversion for you, so measure in whatever the tape gives you and pick the unit.
L-shaped and irregular rooms. Cut the floor into rectangles, work out each one, then add them. An L-shaped room is two rectangles — that is what the second pair of fields is for. Any shape at all can be handled this way as long as the pieces do not overlap, which is also how surveyors do it.
Circles and triangles. A round room is π × radius² — a 12 ft diameter circle is 3.1416 × 6² = 113 sq ft. A triangle is base × height ÷ 2. Both go straight into the running total alongside your rectangles.
Why you buy more than you measure. Flooring is cut to fit, and offcuts at the walls cannot always be reused. The trade standard is 10% extra for a straight-laid floor and 15% for diagonal or herringbone patterns, before rounding up to whole boxes. The calculator adds 10%; add the rest yourself if your pattern is not square to the walls.
Room area is not house square footage. Adding up your rooms will not match the figure on a listing. Gross living area is measured to the outside face of the exterior walls and counts the wall thickness, hallways and stairs, while excluding the garage, an unfinished basement and anything without permanent heat. Room-by-room floor area is the number you want for flooring and paint; gross living area is the number you want for a valuation, and they are meant to differ.
Multiply the length by the width, both in feet. A room 12 ft by 16 ft is 12 × 16 = 192 square feet. If the room is not a rectangle, split it into rectangles, work out each and add the results together.
144 square feet. That is 13.4 square meters, or 16 square yards. Allowing 10% for waste you would buy 159 sq ft of flooring.
Multiply by 10.7639. One square metre is 10.76 square feet, because a metre is 3.2808 feet and the conversion is squared. Going the other way, multiply square feet by 0.0929.
Treat it as two rectangles. Measure the long leg, measure the short leg, calculate each as length × width and add them. Take care not to count the corner where they meet twice — measure the second rectangle only from where the first one stops.
12.5 ft. Inches are twelfths of a foot, so divide the inches by 12 and add: 6 ÷ 12 = 0.5. Writing it as 12.6 is the single most common measuring error, and on a 12 ft wide room it puts you out by more than a square foot.
10% over the measured area for a floor laid square to the walls, 15% for diagonal or herringbone, then round up to whole boxes. On a 200 sq ft room that is 220 sq ft, which at a typical 20 sq ft per box is eleven boxes.
For flooring and paint, no — you want the floor you can actually see. For a listing or an appraisal, yes: gross living area is measured to the outside of the exterior walls under the ANSI standard, which is why that figure always comes out larger than adding up your rooms.