Carpet Calculator
Enter your room size and the roll width to calculate how much carpet to order in square yards or square meters — including the offcut you pay for but never lay.
Unit
Room dimensions (feet)
Carpet is sold off a fixed-width roll, so the roll width matters as much as the room size. This calculator lays the strips the cheaper way round and adds your waste buffer. Stairs, closets and hallways should be measured and added separately.
Frequently asked questions
How do I calculate how much carpet I need?
Measure the room's length and width, then work out how many full-width strips come off the roll to cover it. Multiply the number of strips by the room length to get the roll length you buy, and add a waste buffer. Ordering by floor area alone under-orders whenever the room is wider than the roll.
Why do I have to buy more carpet than my floor area?
Carpet comes off a fixed-width roll — usually 12 ft, sometimes 13 ft 6 in or 15 ft. If your room is 13 ft wide and the roll is 12 ft, you buy a second strip and the leftover from it is still paid for. A room slightly wider than the roll is the most wasteful case, so ask the retailer about a remnant or a wider roll before committing.
Is carpet sold by the square foot or the square yard?
In the US, broadloom carpet is almost always priced per square yard, and one square yard is nine square feet. Quotes given per square foot are usually comparing a different product, so convert before comparing prices. Outside the US carpet is priced per square meter.
How much waste should I allow for carpet?
Around 5% for a simple square room, 10% for a standard room, and 15% when there are alcoves, a bay window, stairs, or a pattern that has to match across strips. Patterned carpet is the expensive case because every strip must line up with its neighbour.
Do I measure closets and doorways?
Yes. Measure into closets and out to the doorway threshold, because the carpet runs to those points. Stairs are measured separately — a standard step needs roughly the tread depth plus the riser height of carpet, plus a nosing allowance.
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See the colour and pile in your own room before the installer cuts the roll.
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