The formula in one line
Length per step = tread depth + riser height + nosing allowance. Multiply by the number of steps, add landings, add waste, then divide by 36 for linear yards.
Linear yard vs square yard
A linear yard is 36 inches of length off the roll at whatever width the roll happens to be — usually 12ft. A square yard is 9 square feet of surface. For stairs you buy linear, but suppliers often quote square, so you need both numbers.
Quick chart by step count
| Steps | Length per step | Total run | Linear yards (+10%) |
|---|---|---|---|
| 10 | 18 in | 180 in | 5.5 yd |
| 13 | 18 in | 234 in | 7.2 yd |
| 14 | 18 in | 252 in | 7.7 yd |
| 16 | 18 in | 288 in | 8.8 yd |
| 16 | 19.5 in (wrapped nosing) | 312 in | 9.5 yd |
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Open the stair runner calculatorTurning linear yards into square yards
If you are fully carpeting the stairs rather than laying a runner, the supplier will price by the square yard. Multiply the total run by the finished carpet width, then divide by 1,296 to get square yards.
| Stair width | 13 steps | 16 steps |
|---|---|---|
| 36 in | 6.5 sq yd | 8.0 sq yd |
| 42 in | 7.6 sq yd | 9.3 sq yd |
| 48 in | 8.7 sq yd | 10.7 sq yd |
Where the yardage quietly grows
- Wrapped nosings add roughly 1 to 1.5 inches per step.
- Patterned carpet needs a full pattern repeat added to every separate cut piece.
- Landings are measured as flat rectangles and added on top.
- Winders eat far more than a straight step — allow the widest point of the tread.
- Roll width dictates how many strips you can cut side by side; an awkward width wastes metres.
Whatever you decide, get the numbers first: the stair runner calculator doubles as a stair runner length calculator, adding nosing wrap, landings, winders, pattern repeat and waste so you order the right length the first time.
Frequently asked questions
How many yards of carpet do I need for 13 stairs?
Around 7 linear yards for a standard 13-step flight with 11in treads and 7in risers, once a 10% waste margin is included. Wrapping the nosings or matching a pattern pushes it closer to 8.
Is carpet for stairs sold by the linear or square yard?
Broadloom carpet is sold by the linear yard off a roll of fixed width, but many retailers quote a square-yard price. Ask which one the number refers to before comparing quotes.
How much extra carpet should I buy for stairs?
Ten per cent on plain carpet, and one extra full pattern repeat per cut piece on patterned carpet. Buying an extra half-yard for future repairs is cheap insurance against a discontinued line.
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Calculate my carpet yardage