Enter up to three rooms by length and width, or a square footage you already know, and
get the carpet you need in square feet and square yards — plus matching padding.
A waste factor is built in (10% by default, more for stairs and patterns) so you don't
come up short. Carpet is sold by the square foot or the square yard, so you get both.
Square feet & square yards·Up to three rooms or direct area·Carpet plus padding
Read this first
This is a material estimate based on floor area plus a flat waste factor, not a
cutting plan. Carpet comes on rolls 12 feet wide (sometimes 15 feet), so a room wider than
the roll needs a seam and leaves offcuts — which means your real purchase, especially
for patterned carpet, is often a bit more than a simple area calculation. Use this number to
plan a budget and sanity-check a quote; let your installer confirm the final order once they
have measured and planned the seams.
The calculator
Estimate carpet and padding
Choose how you want to enter the area, fill in your measurements, and you'll get the total carpet in square feet and square yards with waste applied, plus the matching padding area.
Room 1
Room 2
Room 3
Enter at least one room. For an L-shaped room, split it into rectangles and use the extra rows.
Enter the total square footage you've already measured.
10% is a common default; use about 15% for stairs, hallways, diagonal layouts, or patterned carpet.
Padding covers the same floor as the carpet; the extra is just for trimming.
Floor area (measured)
Carpet (square feet)
Carpet (square yards)
Waste applied
Padding (square feet)
The math, honestly
How the carpet figure is worked out
It's all floor area. For each room, the area in square feet is
length × width, with both in feet, and the rooms are added together
for the total. Then a waste factor is applied: area × (1 + waste/100).
At the 10% default, a 180 sq ft room becomes 180 × 1.10 = 198 sq ft.
To convert square feet to square yards — the unit many carpet
stores and installers still price in — divide by 9, because a
square yard is a 3 ft × 3 ft square, which is 9 square feet. So
198 ÷ 9 = 22.0 square yards. Padding covers the same
floor as the carpet, so it's figured at the room's square footage; you can apply the same
waste factor if you want a little extra for trimming.
Why the waste factor matters: carpet is cut from a roll, so you always
lose some to trimming and to the seam overlap where two pieces meet. Most broadloom comes
on a 12-foot-wide roll (some styles in 15 feet), so a room wider than the
roll forces a seam and leaves an offcut that's often unusable. Stairs, hallways, diagonal
layouts, and patterned carpet all waste more — which is why 15% is the safer factor
there. This is a material estimate; an installer plans the actual seam placement.
Common room sizes
Worked examples for a few common room sizes, computed with the same formula and a 10%
waste factor — so these match what the calculator gives you. The square-yard column
includes the waste; carpet is what you'd buy, and padding equals the raw floor area.
Room
Floor arealength × width
Carpet sq ft+10% waste
Carpet sq yd÷ 9, with waste
10 × 12
120 sq ft
132 sq ft
14.7 sq yd
12 × 12
144 sq ft
158 sq ft
17.6 sq yd
12 × 15
180 sq ft
198 sq ft
22.0 sq yd
14 × 16
224 sq ft
246 sq ft
27.4 sq yd
15 × 20
300 sq ft
330 sq ft
36.7 sq yd
20 × 20
400 sq ft
440 sq ft
48.9 sq yd
Square yards are square feet divided by 9, with the 10% waste included and rounded to one
decimal. Padding is figured at the raw floor area in the first column. Rooms wider than the
12-foot roll (like the 14-, 15-, and 20-foot rooms here) will need a seam, which can push
real waste above the flat 10%.
Reading the result well
An area number is only useful if you act on it sensibly. Four things worth knowing before
you order.
Match the waste factor to the job
Ten percent covers trimming and a normal seam for a simple rectangular room. Bump it to about 15% for stairs, hallways, diagonal or herringbone layouts, and any patterned carpet that has to be matched across seams. Pattern repeat is the biggest waste driver: matching the design can force you to cut and discard a strip on every seam, sometimes pushing waste well past 15%.
The 12-foot roll changes the real number
Most broadloom carpet comes on a roll 12 feet wide, with some styles in 15 feet. A room wider than the roll needs a seam, and the leftover strip is often unusable, so a 14-foot-wide room can waste far more than a flat percentage suggests. Where a seam falls — and whether your room fits within a single roll width — has a real effect on how much carpet you buy. A good installer hides seams in low-traffic, low-visibility spots.
Don't skip the padding
Most residential carpet needs padding underneath for comfort, insulation, and longevity, and many warranties require it. Padding covers the same floor area as the carpet, so order it at the room's square footage. This calculator reports padding at the measured area by default; switch it to match the carpet's waste factor if you want a little extra for trimming around the edges.
Know both units before you shop
Many stores now price carpet by the square foot, but older pricing, some installers, and a lot of online guidance still quote by the square yard. Knowing both numbers (divide square feet by 9 for square yards) lets you compare quotes apples-to-apples and catch a price that looks low only because it's stated in the smaller unit.
Where to buy
Got your numbers? Here's where to pick up what you need:
The terms behind the calculator, in plain English. These are background definitions, not
installation specifications — let your installer plan the actual layout and seams.
Square foot
A square one foot on each side. It's the working unit for measuring a room: multiply length by width, both in feet, to get the floor area. Many carpet stores now price by the square foot.
Square yard
A square three feet on each side, equal to 9 square feet. It's the traditional unit for selling carpet, and many installers still quote in it. Convert from square feet by dividing by 9; that's why a 198 sq ft room is 22 square yards.
Waste factor (overage)
The extra carpet bought above the measured floor area — typically 10%, or about 15% for stairs, hallways, diagonal layouts, and patterned carpet — to cover trimming, the seam overlap, and offcuts left when a room is wider than the roll. It's cheap insurance against coming up short.
Broadloom
Carpet manufactured and sold in wide continuous rolls, as opposed to carpet tiles. Standard broadloom comes on a 12-foot-wide roll, with some styles in 15 feet and occasionally 13 ft 6 in. The fixed roll width is the main reason real waste can exceed a flat percentage.
Seam
The join where two pieces of carpet meet, needed whenever a room is wider than the roll or shaped so a single piece won't cover it. Seams waste a little carpet to the overlap and are planned to fall in low-traffic, low-visibility areas. More seams generally means more waste.
Pattern repeat
The distance over which a carpet's design repeats. To make a pattern line up across a seam, the installer may have to shift a piece and discard the offcut, so patterned carpet wastes more than a plain one — use a higher waste factor and expect a larger order.
Padding (carpet cushion)
The cushioning layer installed under the carpet for comfort, insulation, and durability; many warranties require it. Padding covers the same floor area as the carpet, so it's figured at the room's square footage rather than the carpet's with-waste figure.
Frequently asked
Multiply the room's length by its width in feet to get the floor area in square feet, then add a waste factor of about 10% for trimming and the seam. A 12 ft × 15 ft room is 180 sq ft; with 10% waste that's 198 sq ft, or about 22 square yards once you divide by 9. For an irregular room, split it into rectangles, figure each, and add them up — the calculator takes up to three rooms.
Divide the square footage by 9. A square yard is a 3 ft × 3 ft square, which equals 9 square feet, so square yards = square feet ÷ 9. For example, 198 sq ft ÷ 9 = 22 square yards. Many stores price by the square foot now, but installers and older quotes often use the square yard, so it helps to know both.
Add about 10% over your measured floor area for a simple rectangular room, and about 15% for stairs, hallways, diagonal or herringbone layouts, and patterned carpet matched across seams. The waste covers trimming, the seam overlap where two pieces meet, and the offcuts left when a room is wider than the 12-foot roll. Pattern repeat is the biggest driver, because matching the design can force a discarded strip on every seam.
Most residential carpet needs padding underneath it for comfort, insulation, and longer life, and many warranties require it. Padding covers the same floor area as the carpet, so figure it at the room's square footage. This calculator reports padding at the measured area by default, and you can switch it to match the carpet's waste factor if you want a little extra for trimming around the edges.
Stairs use more carpet than they look like they should, because every step has a tread you walk on and a riser facing you. A common rule of thumb is roughly 1.5 to 2 square feet of carpet per step for the combined tread and riser, plus a bit extra to wrap the nosing. Because stairs mean many small cuts and seams, use a higher waste factor (around 15%) and confirm with your installer — wrapped and waterfall installations use different amounts.
Most broadloom carpet is sold on rolls 12 feet wide, with some styles in 15 feet and occasionally 13 ft 6 in. The roll width matters because a room wider than the roll needs a seam, and the leftover strip is often unusable — which raises real waste above the simple percentage. Where the seam falls, and whether a single roll width can cover the room, has a real effect on how much carpet you end up buying.
There are 9 square feet in one square yard. A square yard is a square 3 feet on each side, and 3 × 3 = 9. To convert a carpet area from square feet to square yards, divide by 9; to go the other way, multiply square yards by 9.
This is a material estimate based on floor area plus a flat waste percentage. A real installer's quote also accounts for the fixed 12-foot roll width, the direction the pile must run so the carpet looks consistent, the pattern repeat, where seams can be hidden, and the offcuts that fall out of all of that. Those factors usually push the real purchase above a simple area calculation, especially in rooms wider than 12 feet or with patterned carpet. Use this number to sanity-check a quote, not as a final order quantity.