Carpet Quantity Calculator — Sq Yd for Rooms & Stairs
Carpet Quantity Calculator
How much carpet do you need? Answer in square yards — for a room, or for stairs. No sign-up, no account, free to use.
Do it in 3 steps
- Step 1 — Measure. For a room, measure length and width. For stairs, count the steps and measure one tread and one riser.
- Step 2 — Choose waste. Keep Straight 10% for a plain room, or pick Custom if your carpet pattern needs more.
- Step 3 — Check the square yards. Read the big sentence in the green box. That is how much carpet to order.
Why square yards?
Carpet shops sell carpet by the square yard, not by the square foot. That confuses many people, so here is the plain rule: 1 square yard = 9 square feet. If your room is 180 square feet, divide by 9 and you get 20 square yards. This calculator does that division for you, then adds your waste on top.
Room size
Example: a room that is 12 feet 6 inches long means Feet = 12 and Extra inches = 6.
Enter your measurements above to see your carpet quantity.
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Save your measurements
Your current measurements are saved on this device automatically. You can also save up to 10 named projects and open them again later. No account is needed.
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Worked example 1 — A room
Room: 12 feet long, 15 feet wide. Waste: 10%.
| Step | Working | Answer |
|---|---|---|
| Area in square feet | 12 × 15 | 180.00 sq ft |
| Area in square yards | 180 ÷ 9 | 20.00 sq yd |
| Waste (10%) | 20.00 × 10 ÷ 100 | 2.00 sq yd |
| Order quantity | 20.00 + 2.00 | 22.00 sq yd |
You need: 22.00 sq yd.
Worked example 2 — Stairs
Stairs: 13 steps. Tread: 10 inches. Riser: 7 inches. Carpet width: 36 inches. Waste: 10%.
| Step | Working | Answer |
|---|---|---|
| Carpet length for one step | (10 + 7) ÷ 12 | 1.4167 ft |
| Total carpet length | 13 × 1.4167 | 18.42 ft |
| Area in square feet | 18.42 × (36 ÷ 12) | 55.25 sq ft |
| Area in square yards | 55.25 ÷ 9 | 6.14 sq yd |
| Order quantity (10% waste) | 6.14 × 1.10 | 6.75 sq yd |
You need: 6.75 sq yd.
How to measure stairs, in plain words
Stand on a step. The flat part under your foot is the tread. The upright part in front of the next step up is the riser. Carpet goes over the tread, bends down over the riser, and continues to the next tread. That is why the calculator adds tread + riser for every step. Measure only one step if all your steps are the same size — most straight stairs are. If your steps are different sizes, measure the biggest step and use that number, so you do not run short.
How much waste should you pick?
For a plain carpet with no pattern to match, 10% is the normal choice. For a carpet with a clear pattern that must line up from one piece to the next, you will lose more carpet at the joins, so use Custom and enter 15% to 20% as a starting point. For a room with many corners, doorways or a bay shape, go higher. Never enter more than 50% — the calculator will stop you, because above that something is usually wrong with a measurement.
What this calculator does not do
- It does not work out the price. Multiply the order square yards by your shop's price per square yard.
- It does not include underlay (padding), fitting, grippers, door bars, or delivery.
- It does not plan seams or the direction the carpet roll will run. A shop or fitter checks that from your room plan.
- It does not measure curved stairs, spiral stairs, or rooms with curved walls. For those, ask a fitter to measure.
- It does not cover a room that is not a rectangle in one go — split it into rectangles as explained in the questions below.
Questions about carpet quantity
Why is carpet sold in square yards, not square feet?
Carpet is sold by the square yard because carpet rolls are measured that way. One square yard equals 9 square feet. This calculator first works out your area in square feet, then divides by 9, so you get the square-yard number the shop will ask for.
How much extra carpet should I order for a room?
For a plain rectangular room, 10% extra is the usual starting point. It covers cutting waste and small mistakes. If your carpet has a large pattern that must line up, use the Custom waste box and enter a higher number, up to 50%.
How do I measure stairs for carpet?
Count the steps. Then measure one tread, the flat part your foot lands on, and one riser, the upright part at the back of the step. Enter those two numbers in inches, plus the carpet width in inches. The calculator works out the carpet length for all the steps together.
What carpet width should I enter for stairs?
Enter the width of carpet you want on the stair, in inches. A common stair runner width is 36 inches. If you want wall-to-wall carpet on the stair, measure the full stair width instead.
What if my room is not a rectangle?
This calculator is for one rectangle at a time. For an L-shaped room, measure the longest length and the longest width for a rough total, or split the room into two rectangles, work out each one here, and add the two square-yard results together.
Does this calculator include the cost of carpet?
No. It only tells you the quantity in square yards. Multiply the order quantity by your shop's price per square yard to get the carpet material cost. Padding, fitting and delivery are not included.