How to measure stairs and landings for carpet

For UK flooring retailers and fitters · 9 minute read · Updated July 2026

Stairs are where flooring estimates go wrong. A rectangular room is arithmetic; a staircase is a series of small, awkward, three-dimensional pieces that all have to run the same way and meet neatly at the nosings. Get it wrong by 10% and you're either back to the supplier for a second length that won't match, or you've eaten the cost of a metre you didn't need.

This is how the trade measures stairs properly — and how to plan the cuts so the stairs come out of carpet you've already had to buy.

The tread-plus-riser method

Carpet on a staircase runs continuously over the front edge of each step and down the vertical face below it. So each step consumes the depth of the tread, plus the height of the riser, plus a small amount to wrap around the nosing at the front.

Take a typical UK domestic staircase: a tread of 250mm and a riser of 200mm. Add 25mm for the nosing and each step needs 475mm of carpet down the run. A 13-step flight therefore needs roughly 6.2 linear metres.

The width is simpler: measure the staircase at its widest point and add about 50mm for trimming. Most domestic stairs come out at 800–900mm. That's your strip — 900mm wide by 6.2m long, in the example above.

Step by step

1. Measure one tread and one riser. Take them from the middle of the flight, not the top or bottom step — those are often slightly different. Add 25mm for the nosing.
2. Count the steps. Include the top step if it's carpeted as part of the flight rather than as part of the landing. This is the single most common counting error.
3. Multiply for the run length. Tread + riser + nosing, times the number of steps.
4. Measure the width at the widest point, and add 50mm for trimming. If it's a runner rather than full width, measure the runner width and note the exposed timber each side.
5. Measure winders individually — see below. Never average them.
6. Measure the landing as its own rectangle, longest by widest, plus a trimming allowance.
7. Note the pile direction every piece has to run in, before you plan a single cut.

Winders: measure every one

Winders are the turning steps on a quarter- or half-landing — wedge-shaped, wider at one end than the other. They're where stair estimates leak the most material.

The rule is simple and non-negotiable: a triangular step still needs a rectangular piece of carpet. You cut to the widest point and the longest point, and the rest is offcut. That's not bad practice, it's geometry.

What separates a good estimate from a lazy one is measuring each winder individually. On a typical three-winder turn, the steps are meaningfully different widths. Take one average figure across all three and you'll be short on the widest — which means a visible join, or a trip back to the supplier for carpet from a different dye lot.

Landings

A landing is just a small room, with one complication: it has to agree with the stairs. Measure it as a rectangle — longest point by widest point, plus trimming — but take the measurement including any doorway thresholds the carpet runs into.

The complication is pile. The landing carpet and the stair carpet meet at the top step, in full view, usually under a window. If the pile runs a different way on each, they will shade differently and the customer will see two different colours of the same carpet. That's a callback, and it's an expensive one.

Pile direction: the constraint you plan around

Pile runs down the stairs. Looking up the staircase, you should be looking into the pile — it wears better, and it reads darker and richer from the angle people actually see it from.

This matters for estimating because it means you cannot freely rotate pieces to make them fit the roll. Every stair piece, every winder, and the landing all have to run the same way down the length of the roll. Any cutting plan — whether you're sketching it on graph paper or using software — has to respect that. Naive arithmetic that just tessellates rectangles will give you a lovely-looking figure that can't actually be cut.

Bullnose and curved bottom steps

The bottom step is often a bullnose — rounded at one or both ends, and wider than the steps above it. Measure it separately at its widest point and its deepest point, and allow for the carpet to be worked around the curve. A bullnose typically wants a piece 100–150mm wider than the standard steps, and it's fiddly to fit, not just to measure.

If both ends are bullnosed (a "double bullnose"), measure the full width across both curves. Don't assume symmetry — old staircases rarely are.

Patterned carpet on stairs

Pattern turns a measuring job into a planning job. The repeat has to align across every step, which means cuts can only start at repeat intervals — you're no longer cutting where you like, you're cutting where the pattern lets you.

The practical effect is an extra 15–25% on the order, sometimes more on a large repeat. Two things to do: measure the pattern repeat itself and record it with your dimensions, and quote for the pattern allowance as an explicit line. Customers accept paying for pattern matching when they can see it itemised — and it protects you from absorbing the difference when the roll turns up.

The bit most estimates miss: plan the stairs against the roll

Here's where the money is. Most quotes measure the stairs, then add that length to the order as if it were a separate purchase. It usually isn't.

Carpet comes in fixed roll widths — 4m and 5m for broadloom. A room 3.2m wide, cut from a 4m roll, leaves a strip 800mm wide running the full length of that cut. And a typical domestic staircase is 800–900mm wide.

The stairs, in other words, will often come out of a strip you have already had to buy for the lounge. Planned room-by-room, that strip goes in the skip and the stairs get their own fresh length of roll. Planned as one job, the stairs are effectively free material.

So before you add a single metre to the order for stairs, check what strips the main rooms are leaving behind. It's the single biggest saving available on a whole-house job, and it's the reason we wrote a whole guide on carpet wastage and how to reduce it.

Typical figures, for sanity-checking

These are for checking your arithmetic looks sane — never for quoting. Every staircase is its own animal, and old houses in particular will happily give you three different riser heights in one flight.

Frequently asked questions

How do you measure stairs for carpet?

Measure one tread and one riser, add them together plus about 25mm for the nosing, and multiply by the number of steps. Measure the width at the widest point and add about 50mm for trimming. Winders and landings are measured separately.

How much carpet do I need for 13 stairs?

With a typical 250mm tread and 200mm riser plus nosing, that's about 475mm per step — roughly 6.2 linear metres for 13 steps. On a 900mm-wide staircase, that's a strip 900mm × 6.2m. Always measure the actual stairs rather than trusting the typical figures.

How do you measure winders?

Individually, at the widest point. A wedge-shaped step still needs a rectangular cut, and the waste is unavoidable. Averaging across several winders will leave you short on the widest one.

Which way should carpet pile run on stairs?

Down the stairs — so you're looking into the pile as you look up the flight. It wears better and stops the stairs shading differently from the landing. Pile direction must stay consistent across every piece in the job.

How much extra should I allow for stairs?

10–15% on a straight flight with a landing; up to 30% where there are winders. Patterned carpet adds a further 15–25% on top.