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.
Pad is installed without seams concerns, so it’s calculated from the room 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.
- If the room is wider than the roll, the result includes the extra strip needed for a seam.
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)
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 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.