The stair runner length formula
For a straight flight, the runner has to travel across the flat part of each step and down the vertical face below it. That means:
Runner length = steps × (tread depth + riser height), + nosing, + landings, + waste
Tread is the horizontal surface you stand on. Riser is the vertical face between two treads. Nosing is the lip that overhangs the riser — it only adds length if you wrap it.
Everything else in a stair runner calculation is an adjustment on top of that core number: pattern matching, winder steps, landings, and a waste margin so the fitter has something to trim.
Worked example: 13 steps
Take the most common staircase in a US or UK home — 13 steps, a 10in tread and a 7.5in riser, fitted waterfall style with no nosing wrap.
| Element | Maths | Length |
|---|---|---|
| Treads | 13 × 10in | 130in |
| Risers | 13 × 7.5in | 97.5in |
| Subtotal | — | 227.5in (5.78m) |
| Waste at 10% | 227.5 × 0.10 | 22.75in |
| Total to order | — | 250.25in ≈ 6.36m / 20ft 10in |
Round that up to the next half metre and you would buy 6.5m. If the runner comes on a roll sold by the linear yard, that is 7 yards.
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 calculatorAdjusting for a wrapped (Hollywood) installation
A waterfall installation lets the runner fall straight from the nosing to the next tread, so the nosing adds nothing. A wrapped or Hollywood installation pulls the runner tight around the curve of the nosing, following the profile of the step. That adds roughly twice the nosing depth per step.
With a 1.25in nosing on 13 steps that is an extra 32.5in — nearly a metre. It is the single most common reason a runner order comes up short.
Adding landings
A landing is measured as a simple flat run: the length the runner travels across it, front edge to back edge. Add each landing's length once. If the runner turns on the landing, measure the longest path the runner takes, then add a little extra so the fitter can square the joint.
Adding winder steps
Winder (pie-shaped) steps are always measured at their widest point, because the runner has to be cut to cover the deepest part of the tread. A winder with a 24in widest tread and a 7.5in riser eats 31.5in of runner — three times a regular step. Count winders separately from your straight steps rather than averaging them in.
Pattern repeat allowance
If the runner carries a pattern, the fitter needs freedom to start each flight at the same point in the repeat. The safe rule is to add one full pattern repeat per flight and per landing. On a large-repeat herringbone or a bold stripe that can add 10–15% to the order.
How much waste to allow
| Staircase | Suggested waste margin |
|---|---|
| Straight flight, plain runner | 5–10% |
| Straight flight, patterned runner | 10–15% |
| L-shaped with one landing | 10–15% |
| U-shaped or winders | 15–20% |
Waste is not wasted money. Off-cuts are what a fitter uses to correct a mis-measured step, and a leftover metre is a cheap insurance policy against a dye-lot that no longer matches in two years.
Metres, feet or yards?
Most runners are sold by the linear metre in the UK and Europe and by the linear foot or yard in the US. Convert once at the end, never mid-calculation: 1m = 39.37in, 1ft = 12in, 1yd = 36in. The calculator on this site shows every result in all three so you can order from any supplier.
Worked example: a 16-step staircase with a landing
Larger homes often have a 16-step flight broken by a half landing. Say the flight splits into 8 steps, a 42in landing, then another 8 steps, with the same 10in tread and 7.5in riser as before.
| Element | Maths | Length |
|---|---|---|
| Lower flight | 8 × 17.5in | 140in |
| Landing | 1 × 42in | 42in |
| Upper flight | 8 × 17.5in | 140in |
| Subtotal | — | 322in (8.18m) |
| Waste at 15% | 322 × 0.15 | 48.3in |
| Total to order | — | 370.3in ≈ 9.4m / 30ft 10in |
Notice the waste margin jumps from 10% to 15% purely because a landing is involved — that extra allowance covers the trim and square cut the fitter needs at the joint, not a second helping of caution.
Why the formula ignores stair width
Length and width are independent calculations, and conflating them is a common beginner error. Width only affects how much runner you need across each step; length is purely a function of how many steps there are and how deep each one runs. Work out width separately using the stair runner width calculator, then run the length numbers on their own.
Where people over-order and under-order
| Error | Typical cause | Typical impact |
|---|---|---|
| Under-ordering | Forgetting nosing wrap or landings | 0.5–1m short, a second delivery |
| Over-ordering | Applying waste twice, or to width as well as length | 1–2m of unused, unreturnable runner |
| Wrong unit conversion | Mixing metric supplier quotes with imperial site measurements | Order arrives noticeably short or long |
Order to a whole number your supplier stocks
A supplier selling in half-metre or full-foot increments will round your figure anyway. Do the rounding yourself so you know exactly what you are paying for before you check out.
How fitters use the leftover
A competent fitter treats the calculated waste margin as working material, not a discount. It gets used to true up a step that turns out deeper than the average, to replace a section damaged during fitting, or — kept safely afterwards — to patch a worn tread years later without a mismatched dye lot. Ask your fitter to hand back any substantial off-cut rather than binning it.
Sense-checking your final figure
Before you order, run a rough gut check: a typical straight flight of 12–14 steps in a domestic home almost always lands between 5.5m and 7m of finished runner once waste is included. If your total comes out well outside that range, recheck which unit you measured in and whether you have accidentally doubled up an allowance.
Converting your final figure for checkout
Once you land on a total, write down all three units side by side — metres, feet and yards — before you go to a supplier's site. Some sellers list price per linear yard, others per linear metre, and a quick mental slip between the two on a $60/yard runner can mean a genuinely large budgeting error. Keep the conversion note with your order reference so a follow-up query or reorder months later starts from the same figures.
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.
Still deciding on material, width or pattern? Our hub on stair runners compares weaves, widths, backings and fitting styles side by side, then hands the numbers straight to the calculator.
Frequently asked questions
How much stair runner do I need for 13 steps?
For 13 standard steps with a 10in tread and 7.5in riser, allow about 5.8m (19ft) of runner before waste, and roughly 6.4m (21ft) once you add a 10% margin. Wrapping the nosings or adding a landing pushes that higher.
Do I include the top step in my measurement?
Count every tread the runner will cover. The top step is often a landing edge rather than a full step, so check whether the runner finishes at the nosing of the top tread or carries onto the landing floor — the two differ by up to a full step's worth of material.
What happens if I order too little runner?
Most suppliers can cut more from the same roll if you order again quickly, but dye lots vary batch to batch, so a delayed top-up can show as a subtle colour break at the join. Always order your waste margin up front rather than relying on a second cut.
Does runner length change if the stairs are open on one side?
No. Length depends on tread depth, riser height and step count regardless of whether one side is open with a balustrade or boxed in by two walls. Width is what changes on an open-sided staircase.
Can I use the same formula for a spiral staircase?
Only loosely. Spiral and heavily curved stairs have treads that vary dramatically in depth from the inside to the outside edge, so tread-plus-riser per step is measured individually rather than averaged, and waste allowances run higher, typically 20% or more.
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 lengthEvery 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.