Carpet Calculator
Carpet comes off a fixed-width roll, so the real question isn't just floor area — it's how your room fits that roll. Enter the room size and roll width and get the square yards to buy, the seam count, the waste, and the padding, with the layout chosen to waste the least.
One rectangular room. For odd shapes, measure the bounding rectangle the carpet has to cover.
Prefilled from the choice above — confirm the roll width of your specific carpet.
Advanced: padding & price
Leave padding price blank if you're only pricing carpet.
Formula & how it works
For each direction, strips = room dimension ÷ roll width rounded up, and roll length = strips × the other dimension. The calculator keeps whichever direction needs less roll.
Buy = roll length × (1 + waste) rounded up to whole feet, times roll width, converted to square yards (÷ 9). Seams = strips − 1. Padding = room area plus a small trim margin.
Worked example
A 12 × 15 ft room on a 12 ft roll: because the room is 12 ft in one direction, a single strip 15 ft long covers it with no seam. With 10% waste that's about 17 ft of roll — roughly 23 yd² — against 20 yd² of actual floor. A 20 × 15 ft room needs two strips and one seam, about 44 yd².
Buying carpet without overpaying
Roll width, not just area, sets the cost
Two rooms with the same floor area can need very different amounts of carpet depending on how they line up with the roll. A room within the roll width in one direction may need no seam and little waste; nudge it wider and you're suddenly buying a whole extra strip. Getting the roll width right — and confirming it for your exact carpet — is the difference between a tight estimate and an expensive surprise.
Seams have rules
Seams should fall in low-traffic, low-light spots and run the same direction as the main sightline, and the carpet's nap (pile direction) should be consistent across every piece or the seams will show as a color shift. That's why installers sometimes choose a layout with slightly more waste to place a seam better — treat this tool's layout as the material-minimizing option, not the only valid one.
Don't forget the padding and the pros
Padding is a separate purchase sized to the room area, and it matters for comfort, wear, and often the warranty. And because carpet can't be pieced together like tile, measuring and seaming is genuinely a pro skill — this estimate is for budgeting and comparing quotes, with the installer taking the final field measurements.