Measure every tread, not just one
Staircases are rarely perfectly parallel. Measure the tread width at the narrowest point, usually the top or bottom step where skirting or a newel post intrudes, and use that figure as your governing width.
Reveal margins
| Reveal each side | Look | Best for |
|---|---|---|
| 2 in (5 cm) | Traditional, generous stained-wood border | Period staircases |
| 3 in (7.5 cm) | Balanced, most common choice | Most homes |
| 4-5 in (10-12.5 cm) | Runner reads as narrow, modern | Wide treads, contemporary schemes |
Worked example
A tread measuring 38in (96.5cm) wall to wall with a 3in (7.5cm) reveal each side needs a 32in (81cm) runner, which is the closest stock width. On a 36in (91cm) tread with the same reveal you land close to 30in (76cm), so most suppliers would round down to 27in for a slightly larger reveal or up to 32in for a smaller one.
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 calculatorStandard stock widths
| Stock width (in) | Metric equivalent | Typical tread it suits |
|---|---|---|
| 22 in | 56 cm | Narrow cottage stairs |
| 27 in | 68 cm | Standard flight, 33-39in tread |
| 32 in | 81 cm | Wider flights, 38-44in tread |
| 36 in | 91 cm | Grand or open-plan staircases |
- Measure at least three points along the flight: top, middle, bottom.
- Account for handrail brackets or radiators that intrude on width.
- Round down to the nearest stock width if you are between sizes and prefer a larger reveal.
- Custom widths are available but cost 15-30% more than stock sizes.
Winders need special care
On winder or curved stairs the tread width changes across the turn. Measure each winder individually rather than assuming the straight-flight width carries through.
Worked example with real numbers
To see how how to measure a stair runner for width plays out on an actual staircase, take a common 13-step flight with a 10 in (25 cm) tread depth and a 7.5 in (19 cm) riser height. That gives 17.5 in (44 cm) per step, or 227.5 in (5.78 m) of raw length before any waste allowance is added, a figure worth keeping in mind whenever this topic is discussed in isolation from the rest of the job.
| Measurement | Imperial | Metric |
|---|---|---|
| Tread depth | 10 in | 25 cm |
| Riser height | 7.5 in | 19 cm |
| Per step total | 17.5 in | 44 cm |
| 13 steps, raw length | 227.5 in | 5.78 m |
| With 8% waste allowance | 245.7 in | 6.24 m |
When to call a professional instead
Plenty of homeowners handle how to measure a stair runner for width themselves on a straightforward straight flight, but certain conditions tip the balance firmly towards hiring a fitter. Getting a second opinion before committing materials often costs nothing and can save an expensive mistake on a job that cannot easily be undone.
- The staircase has a turn, winders, a curve or a split level rather than one straight run.
- The existing substrate is damaged, damp, or its condition is genuinely unclear.
- The runner is an expensive natural fibre or bespoke pattern where a cutting mistake is costly.
- You have no experience with a staple gun, knee kicker or carpet seaming on stairs.
- The staircase is the main one in the home and downtime or an unfinished look is not acceptable.
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
What width stair runner do I need?
Measure your narrowest tread wall to wall, then subtract twice your intended reveal (commonly 2-4in per side). Round to the nearest stock width: 27in, 32in or 36in are the most common.
Is 27 inch or 32 inch runner more standard?
27in (68cm) is the most common width in the US and UK, suiting treads around 33-39in wide with a 3in reveal each side. 32in suits wider treads.
Should I measure the tread or the staircase width?
Measure the tread itself, wall to wall or wall to spindle, at its narrowest point. Do not measure the overall staircase opening, which can be wider than the usable tread.
Can a stair runner be custom width?
Yes, most suppliers cut broadloom carpet to any width and bind the edges to order, typically at a 15-30% premium over stock runner widths.
What is the biggest mistake people make with this?
Rushing the measuring or prep stage. Most poor outcomes with how to measure a stair runner for width trace back to a single measurement taken at the wrong point, or a substrate check skipped to save a few minutes, both far cheaper to fix before the runner is cut than after.
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 runner widthEvery guide is written from hands-on measuring and fitting experience, checked against the calculator’s own maths, and re-reviewed whenever prices or methods change. Read our editorial standards.