About this calculator
Carpet is cut from rolls that are usually 12 ft wide, so the amount you pay for depends on how the room lines up with the roll — not just on floor area. This calculator lays the room out both ways, picks the orientation that wastes the least, adds a trimming allowance and gives the result in square yards, the unit most carpet is priced in.
The drawing shows the room to scale with every strip as it comes off the roll, the seams dashed and the offcut that hangs past the wall, so you can see where a seam would fall before you order. Pad is laid in pieces that are butted together, so it’s bought by the floor area.
How to use it
- Measure the room’s length and width at the widest points, into doorways to the middle of the door.
- Choose the roll width. Most US carpet is 12 ft; some is 15 ft or metric 4 m.
- Enter the price per square yard to estimate cost.
- Check the drawing: if the room is wider than the roll, a second strip and a seam are added. Try the other roll widths to see which one avoids the seam or the big offcut.
The formula
Strips = room width across the roll ÷ roll width, rounded up
Length off the roll = strips × (room length + 6 in trimming)
Carpet = length off the roll × roll width (÷ 9 for square yards)
Offcut = carpet − room length × room width
The calculator tries running the roll both along the length and along the width of the room and uses whichever needs less carpet. The 6 in per strip covers trimming at the walls.
Worked example
These are the calculator’s starting values and the results they produce:
| Room length | 14 ft |
|---|---|
| Room width | 12 ft |
| Roll width | 12 ft (most common) |
| Price per square yard | $30.00 |
Tips before you buy
- Seams should run toward the main light source (usually a window) and away from high-traffic paths so they’re less visible.
- Pile direction must match across seams — never turn a piece 90° to save carpet.
- For stairs, measure one tread plus riser (usually 18–20 in per step), multiply by the number of steps, and let the installer confirm — stairs are cut individually.
- Get an installer’s measurement before ordering for irregular rooms; they plan seams and fills to minimize waste.
Frequently asked questions
How many square yards of carpet do I need for a 12×14 room?
The room is 168 sq ft (18.7 sq yd). Off a 12 ft roll you need one strip 14.5 ft long including trimming — 174 sq ft, or 19.3 square yards.
How many square yards of carpet for a 12×12 room?
The floor is 144 sq ft, exactly 16 square yards, and that is what the pad covers. The carpet off a 12 ft roll is one piece 12 ft 6 in long: 150 sq ft, or 16.7 square yards.
My room is 14×13 ft. Should I buy a 12 ft or a 15 ft roll?
A 15 ft roll if the carpet comes in that width. On a 12 ft roll the room needs two strips 13 ft 6 in long and a seam: 324 sq ft, or 36 square yards, for a 182 sq ft floor (44% offcut). A 15 ft roll covers it in one piece 13 ft 6 in long: 202.5 sq ft, or 22.5 square yards, with no seam.
How do I convert square feet to square yards?
Divide by 9. One square yard is 3 × 3 ft = 9 sq ft.
Why do I need more carpet than my room’s area?
Carpet comes in fixed-width rolls. If a room is 13 ft wide and the roll is 12 ft, you need a second strip to fill the extra foot, and the unused part of that strip is waste unless it can fill closets or doorways.
Sources
Areas and volumes are standard geometry. The published figures this calculator relies on come from these sources; other defaults (waste allowances, typical densities and prices) are common trade figures worth checking with your supplier.
- NIST Handbook 44, Appendix C: general tables of units of measurement: 1 square yard = 9 square feet
- NIST: unit conversion: metric sizes: 1 ft = 0.3048 m exactly