Square footage calculator: rooms in feet and inches
Add up a room — or several — as rectangles in feet and inches, take away anything the floor stops at, and get square feet and square yards with the waste on top.
Advanced settings10% waste
5–10% for a straight lay is where most flooring makers start; more for a diagonal
Floor area
248.0sq ft
Square yards
27.56
With 10% waste
272.8 sq ft
In square yards
30.31
Where the number comes from
- 1. 16' × 13' 6"
- + 216.0 sq ft
- 2. 12' × 3' 6"
- + 42.0 sq ft
- 3. 5' × 2'Taken away
- − 10.0 sq ft
- Net floor area27.56 sq yd at 9 sq ft to the yard
- 248.0 sq ft
- Plus 10% wasteOn the net area — nobody buys spare for the hearth
- 272.8 sq ft
Measuring a room for this
Measure wall to wall at floor level, to the nearest inch, and split anything that is not a rectangle into rectangles that are: an L is two, a bay is one more. Measure each room twice in different places — walls are not parallel, and the bigger reading is the one to use.
Flooring and tile are sold by the square foot and carpet by the square yard; the waste figure is the one on the box when the box gives one.
Worked example: two rectangles added, one taken away
16' × 13' 6" and 12' × 3' 6" add up to 258.0 sq ft; taking away 5' × 2' leaves 248.0 sq ft, or 27.56 sq yd at nine square feet to the yard.
With 10% added for cuts on the net area, buy flooring for 272.8 sq ft (30.31 sq yd).
- Net floor area
- 248.0 sq ft
- Square yards
- 27.56
- With 10% waste
- 272.8 sq ft
These are the figures the calculator above opens on. Change any field and it works the same problem for your numbers.
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About square footage
- How do I work out the square footage of a room?
- Multiply the length by the width, both in feet. Inches have to become a fraction of a foot first — 6" is half a foot, not six tenths — so a room 12' 6" by 10' is 12.5 × 10 = 125 sq ft. Typing 12.6 instead is the most common way to get it wrong, and the calculator above takes 12' 6" as written so you never have to convert.
- How do I find the square footage of an L-shaped room?
- Split it into rectangles that do not overlap and add them. A 16' × 12' room with an 8' × 6' alcove off it is 192 + 48 = 240 sq ft. Anything the floor stops at — a hearth, a kitchen island, a built-in — is a rectangle taken away rather than added.
- How many square feet are in a square yard?
- 9. A yard is three feet, so a square yard is three feet by three feet. Divide square feet by 9 to get square yards: a 12' × 12' room is 144 sq ft and 16 sq yd. Carpet and some sheet vinyl are still priced by the yard, which is why the calculator gives both.
- How much extra flooring should I buy?
- Most flooring makers' installation guides start at 5–10% for a plain room laid straight, and more for a diagonal or herringbone lay, where every edge piece is an angled cut. The calculator defaults to 10% and adds it to the net area — after anything taken away — because there is no point buying spare for the part of the room you are not covering. If the box gives its own figure, use that.
You might also need
- Flooring calculatorHow many rows, how wide to rip the first one, and where the end joints fall so they never line up.
- Carpet calculatorSquare yards of carpet off a 12', 13' 6" or 15' roll, laid out in drops with the seams marked, plus stairs and pad.
- Tile calculatorFull tiles across the middle and a sized cut tile at every edge, centred or started from one wall.
- Feet-inch construction calculatorA pocket construction calculator on screen: feet, inches and fractions on a keypad, square and cubic footage, metric, and pitch, rise, run and diagonal from any two.