How Many Square Feet Is a 15x20 Room?
Total area
300 sq ft
Fifteen feet by twenty feet.
How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Length15 ft
- Width20 ft
- How many rooms or areas this size1
- Extra area to add0 sq ft
Total area300 sq ft
| One area | 300 sq ft |
|---|---|
| Times 1, plus extra | 300 sq ft |
| Square yards | 33.33 |
| Square meters | 27.87 |
| Perimeter of one area | 70 ft |
What else matters here
Three hundred square feet, which is three roofing squares. A square is 100 square feet of roof, the unit shingles are sold and priced in, and it is the reason a roofer quotes a job in squares rather than in feet.
The trap is that a roof is not the footprint. A 15 by 20 building has 300 square feet of floor and more roof than that, because the roof runs up a slope. A 6 in 12 pitch multiplies the plan area by about 1.118, so 300 becomes 335 square feet, or 3.35 squares before waste and before the overhang. On a 12 in 12 the multiplier is 1.414. Measuring the ground and ordering shingles from it is how a roof comes up short.
What this calculator assumes
- Length times width, times how many areas are that size. For an L shaped room, split it into two rectangles and run this twice.
- Square yards are square feet divided by nine, which is how carpet is still quoted in much of the country.
Questions people ask
How many square feet is a 15x20 room?
300 square feet, which is 33.33 square yards and 27.87 square meters.
What is a roofing square?
One hundred square feet of roof surface. Shingles are sold and quoted by the square, so 300 square feet of roof is three squares.
Is roof area the same as floor area?
No. The roof runs up a slope, so it is always larger. A 6 in 12 pitch adds about 12 percent, and a 12 in 12 adds about 41 percent.
The square footage calculator takes any dimensions you like and hands back the same list.