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Carpet Calculator
Carpet for a room, including waste for cuts, by roll width.
Carpet area to buy
How it works
Room area = length × width Carpet area = room area × (1 + waste%) Length to buy = carpet area ÷ roll width
Worked example: a 5 m by 4 m room is 20 m². With a 10% waste allowance you need 20 × 1.10 = 22 m². From a 4 m wide roll, that is 22 ÷ 4 = 5.50 m of carpet to order.
Frequently asked questions
Why add a waste allowance at all?
Because cuts, pattern matching and doorways use more carpet than the bare floor area. Ten percent covers most rectangular rooms; an irregular room or a patterned carpet may need more.
Does the roll width change the area needed?
No, only the length to order. The area stays the same, but a narrower roll means a longer length off the roll to cover the same floor.
Should I round up the length?
Yes. Order the next sensible length above the calculated figure — carpet is sold by the metre, and running short mid-room is far worse than a small offcut.
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