Carpet Calculator

Home and DIY
EssentialsHealth and FitnessUnit ConvertersMathsGeometryTimeMoneyPowerDIY

Carpet Calculator

Work out how much carpet to buy for a room from its length and width and the width of the roll, the way an installer lays it out: whole strips off the roll, with a trim allowance at each end and the strips run whichever way wastes least. The page gives the room area, the carpet to order in square yards or square meters, the seams, the pad and the cost.

Every figuretap a card to copy its value

How the strips lay out, to scale

Carpet to order by roll width

Roll widths comparedfor your room, best direction each

The room is covered with whole strips cut from the roll, each as long as the room plus a trim allowance of 3 in at each end (75 mm in metric), and the strips are run whichever way needs less carpet. The carpet to order is the number of strips times their length times the roll width; anything left from the last strip is an offcut. Rolls are commonly 12 ft wide in the US, some 13 ft 6 in or 15 ft, and 4 m or 5 m in the UK and Europe. Carpet is priced by the square yard in the US and the square meter elsewhere; there are 9 sq ft in a square yard. Pad is room area plus 5 percent. Real installations can use offcuts as fills where the pile direction allows, so an installer’s measure may be a little lower. The CSV, image and printed report contain the values you entered, nothing preloaded.

How to use this tool

Enter the room’s length and width in feet or meters, measured wall to wall at the longest and widest points and into doorways to the middle of the door. Pick the roll width your carpet comes in. The carpet to order appears at the top, in square yards for feet or square meters for meters, with the room area, the length off the roll, the number of seams and the offcut.

Add a price per square yard or square meter to see the cost, and a pattern allowance if the carpet has a pattern to match. The drawing shows both ways of laying the strips to scale, with the cheaper one marked, and the table compares every roll width for your room.

How the carpet is worked out

Carpet is not bought by floor area alone. It comes off a roll of fixed width, so the room is covered with whole strips cut to the room’s length plus a little extra for trimming at the walls: 3 in at each end here, or 75 mm in metric. The number of strips is the room’s width divided by the roll width, rounded up. The carpet to order is the number of strips times their length times the roll width.

The page works this out both ways round, with the strips along the length and along the width, and uses whichever needs less carpet. Whatever part of the last strip does not fit in the room is offcut. Square yards are square feet divided by 9.

Scale plans of carpet strips: a 12 by 15 ft room in one 12 ft strip needing 20.67 sq yd with no seam, a 14 by 20 ft room in two 12 ft strips needing 38.67 sq yd with one seam and 20 percent offcut, and the same room from a 15 ft roll in one strip needing 34.17 sq yd, beside a table of floor area and carpet to order for common rooms
A room that fits one roll width is cheap to carpet; one a little wider needs a second strip, a seam and a lot of offcut.

Carpet for common room sizes

RoomFloor areaFrom a 12 ft rollSeamsFrom a 15 ft rollSeams
10 x 10 ft11.11 sq yd14 sq yd017.5 sq yd0
10 x 12 ft13.33 sq yd14 sq yd017.5 sq yd0
12 x 12 ft16 sq yd16.67 sq yd020.83 sq yd0
12 x 14 ft18.67 sq yd19.33 sq yd020.83 sq yd0
12 x 15 ft20 sq yd20.67 sq yd020.83 sq yd0
12 x 18 ft24 sq yd24.67 sq yd030.83 sq yd0
14 x 16 ft24.89 sq yd38.67 sq yd127.5 sq yd0
15 x 20 ft33.33 sq yd41.33 sq yd134.17 sq yd0
16 x 20 ft35.56 sq yd44 sq yd155 sq yd1
20 x 20 ft44.44 sq yd54.67 sq yd168.33 sq yd1

Carpet to order with 3 in of trim at each end of every strip, strips run the cheaper way. Floor area is shown for comparison.

A worked example you can check on paper

A bedroom measures 12 by 15 ft, which is 180 sq ft, or 20 sq yd. The carpet comes on a 12 ft roll. Laid with the strip along the 15 ft wall, the 12 ft width takes exactly one strip, cut 15 ft plus 6 in of trim, 15 ft 6 in long. That is 15.5 times 12, 186 sq ft, or 20.67 sq yd to order, with no seam. The other way round would need two strips of 12 ft 6 in, 300 sq ft, so the first layout is clearly better.

Now take a 14 by 20 ft living room. From a 12 ft roll, the best layout is two strips of 14 ft 6 in running across the room: 29 ft of roll, 348 sq ft, 38.67 sq yd, with one seam and 20 percent offcut, because the second strip only needs to be 8 ft wide. From a 15 ft roll the room takes one strip of 20 ft 6 in, 307.5 sq ft or 34.17 sq yd, with no seam. If the carpet comes in both widths, the wider roll saves 4.5 sq yd here.

Seams, pile and layout

Every strip should run the same way, so the pile leans the same way and the color looks even; carpet laid with strips turned against each other shows a visible shade change. Seams wear best where there is little traffic and show least when they run towards the main window rather than across the light. Doorways are a poor place for a seam.

Installers carpeting several rooms often cut them from one roll together and use the offcut from one room as fill in another, as long as the pile runs the same way. That is why a whole house quote can come out below the sum of the rooms. For a single room, the figure here is what you will be asked to buy.

Mistakes that catch people out

Ordering the floor area. A 14 by 20 ft room is 31 sq yd of floor but needs nearly 39 sq yd from a 12 ft roll.

Measuring to the skirting and not into the doorway. Carpet runs to the middle of the door, under the door, to meet the next floor.

Forgetting closets and alcoves. They count, and can change which way the strips run.

Comparing prices per square foot and per square yard. A square yard is 9 sq ft: 3.50 per square foot is 31.50 per square yard.

Leaving out pattern matching. Patterned carpet needs extra at every seam to line the pattern up; add the allowance your supplier gives.

Popular calculations

Each opens the calculator with its own address, and every value can be changed once it is open.

Rooms in feet, 12 ft roll

8 x 10 ft, 11.33 sq yd9 x 12 ft, 12.67 sq yd10 x 10 ft, 14 sq yd10 x 12 ft, 14 sq yd10 x 14 ft, 19.33 sq yd10 x 20 ft, 27.33 sq yd11 x 12 ft, 15.33 sq yd11 x 14 ft, 19.33 sq yd12 x 12 ft, 16.67 sq yd12 x 13 ft, 18 sq yd12 x 14 ft, 19.33 sq yd12 x 15 ft, 20.67 sq yd12 x 16 ft, 22 sq yd12 x 18 ft, 24.67 sq yd12 x 20 ft, 27.33 sq yd13 x 15 ft, 36 sq yd14 x 14 ft, 38.67 sq yd14 x 16 ft, 38.67 sq yd14 x 18 ft, 38.67 sq yd15 x 15 ft, 41.33 sq yd15 x 20 ft, 41.33 sq yd16 x 16 ft, 44 sq yd16 x 20 ft, 44 sq yd18 x 20 ft, 49.33 sq yd20 x 20 ft, 54.67 sq yd20 x 24 ft, 54.67 sq yd24 x 24 ft, 65.33 sq yd

Wider rooms, 15 ft roll

13 x 16 ft, 15 ft roll, 27.5 sq yd14 x 16 ft, 15 ft roll, 27.5 sq yd14 x 20 ft, 15 ft roll, 34.17 sq yd15 x 15 ft, 15 ft roll, 25.83 sq yd15 x 18 ft, 15 ft roll, 30.83 sq yd15 x 20 ft, 15 ft roll, 34.17 sq yd

Rooms in meters

3 x 3 m, 12.6 m²3 x 3.5 m, 12.6 m²3 x 4 m, 12.6 m²3.5 x 4 m, 14.6 m²4 x 4 m, 16.6 m²4 x 4.5 m, 18.6 m²4 x 5 m, 20.6 m²3.5 x 4.5 m, 18.6 m²5 x 5 m, 41.2 m²4.5 x 6 m, 37.2 m²4.5 x 5 m, 5 m roll, 23.25 m²5 x 5 m, 5 m roll, 25.75 m²4.5 x 6 m, 5 m roll, 30.75 m²

How this was checked

The engine was tested in Node against layouts worked by hand: a 12 by 15 ft room on a 12 ft roll gives one strip of 15.5 ft and exactly 186 sq ft, 20.67 sq yd; a 14 by 20 ft room gives two strips across the room, 29 ft of roll and 348 sq ft, against 492 sq ft the other way; the same room on a 15 ft roll gives 307.5 sq ft with no seam; and a 4 by 5 m room on a 4 m roll gives one strip of 5.15 m, 20.6 m². The price, pattern allowance, pad and square yard conversions were checked the same way.

Every address in the lists above was then opened and checked for a distinct title, the right answer, drawings that render, and clean CSV, image and print output containing only that calculation, at desktop, tablet and phone widths.

Common questions

How do I calculate how much carpet I need?

Measure the room’s length and width at the longest points. Divide the width by the roll width and round up to get the number of strips; each strip is the room length plus a few inches for trimming. Strips times strip length times roll width is the carpet to order. Try it both ways round and use the smaller figure.

How many square yards of carpet for a 12 by 15 room?

The floor is 180 sq ft, or 20 sq yd. With a 12 ft roll the room takes one strip 15 ft 6 in long, which is 186 sq ft, so about 20.67 sq yd to order and no seam.

How do I convert square feet to square yards for carpet?

Divide by 9, because a square yard is 3 ft by 3 ft. A 180 sq ft room is 20 sq yd. Carpet in the US is priced by the square yard, so do the same with the amount you order, not just the floor area.

How much extra carpet should I buy?

With a simple rectangular room and the layout on this page, the offcut is the extra, often 3 to 20 percent depending on how the room fits the roll. Add 5 to 10 percent more for patterned carpet that needs matching at the seams, and more for rooms with many corners.

What width does carpet come in?

In the US most broadloom carpet comes 12 ft wide, with some ranges in 13 ft 6 in or 15 ft. In the UK and Europe the usual widths are 4 m and 5 m. A room that fits within one roll width can be laid without a seam.

How much carpet pad do I need?

Pad is ordered to the floor area, not the carpet order, because it is laid in pieces without matching. Allow the room area plus about 5 percent, so a 20 sq yd room needs about 21 sq yd of pad.

Related Calculators and Reference