Why open risers need less runner
On a standard closed staircase the runner wraps down the face of each riser as well as across the tread, which is what the standard tread-plus-riser formula accounts for. With no riser to cover, the runner covers only the tread top and folds slightly under the nosing at the front, cutting the total length needed by roughly a third.
The measuring difference
| Staircase type | Per-step allowance | Extra length allowance | Difficulty |
|---|---|---|---|
| Closed staircase (standard) | Tread + riser depth | Baseline | Moderate |
| Open riser staircase | Tread depth + 2–3 in wrap | 30–40% less than closed | Moderate |
| Open riser with thick treads | Tread depth + 3–4 in wrap | 25–35% less | Moderate |
Fixing without a riser to anchor into
- Staples or tacks go into the top and underside front edge of each tread rather than into a riser face.
- Underlay pads are cut to the tread only and must be secured so they cannot creep forward under the runner.
- Double-sided runner tape along the tread's rear edge helps stop the piece lifting where there is no riser to pin it against.
- On floating or thin treads, check screw or staple length so nothing punches through the underside where it is visible.
Check what shows underneath
Open riser stairs are often viewed from below or from the side, so staples, tape edges and raw carpet backing on the underside of the nosing will be visible. Choose a wrapped nosing finish and neat backing tape.
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 calculatorRunner width considerations
Because the sides of an open riser tread are often visible with no stringer to hide the runner edge, binding quality and colour matter more here than on a closed staircase. A tonal or contrast binding intentionally chosen to be seen from the side reads far better than an unfinished cut edge.
Worked example with real numbers
To see how fitting a stair runner on open riser stairs 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 fitting a stair runner on open riser stairs 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
How much less runner do open riser stairs need?
Roughly 30 to 40 percent less than a closed staircase, since the runner only needs to cover the tread depth plus a small wrap allowance, with no riser face to cover.
How do you fix a stair runner to open riser stairs?
Staples or tacks go into the top and front underside edge of the tread rather than into a riser, and double-sided tape along the rear edge helps prevent the piece lifting or creeping forward.
Does the runner binding matter more on open riser stairs?
Yes. With no stringer to hide the cut edge, the runner's sides are often visible from below or the side, so a neat, deliberate binding finish is worth choosing carefully.
Can any runner be fitted on open riser stairs?
Most runners can, but check tread thickness before choosing fixing method and confirm nothing will punch through or show on the visible underside of the tread.
What is the biggest mistake people make with this?
Rushing the measuring or prep stage. Most poor outcomes with fitting a stair runner on open riser stairs 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.
Measure my open riser stairsEvery 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.