How to Measure for a Stair Runner (Step-by-Step)

What you need

• A retractable tape measure (a flexible dressmaker's tape helps on wrapped nosings)
• A notepad or your phone
• Ten minutes and an empty staircase

The four measurements that matter

1. Number of steps — count treads, not risers. Walk up and count each surface you stand on.
2. Tread depth — front edge of the step to the face of the riser behind it, measured on a middle step.
3. Riser height — the vertical face from the back of one tread up to the front of the next.
4. Stair width — wall to wall, or wall to the inside face of the balusters, measured at the narrowest step.

Measuring the nosing

The nosing is the lip that overhangs the riser. Hook your tape under the overhang and measure from the front edge of the tread back to the riser face — usually 0.75in to 1.5in. You only need this number if you are wrapping the nosing rather than fitting waterfall style, but note it anyway; suppliers ask.

Measuring landings

Measure the straight-line path the runner will take across the landing, in the direction of travel. On a quarter-turn landing that path is an L, so measure both legs and add them. Add 4–6in per landing for the fitter to square and joint the piece.

Measuring winder and pie steps

Winders taper from a narrow inside edge to a wide outside edge. Always measure the widest point of the tread, because the runner has to be cut to cover it. Record each winder separately — on a three-step winder turn the widest points are often quite different.

Common mistakes

Turning measurements into an order

Once you have your four numbers, feed them into the stair runner calculator. It applies the tread-plus-riser formula per step, adds nosing, landings, winders and pattern allowance, applies your waste margin and rounds up to a sensible purchase length in metres, feet and yards.

Measuring stair width the right way

Width errors are less common than length errors but more visible once fitted. Measure at the narrowest tread on the flight — usually near the top or bottom where handrail brackets or wall returns intrude — and measure to the inside face of any balusters, not the outer edge of the tread itself. Use the stair runner width calculator to convert that figure into a standard size and reveal.

Tools worth having beyond a tape measure

A room-by-room measuring checklist

1. Clear the staircase completely, including any stair gates or runners already fitted.
2. Count treads from bottom to top, out loud, twice.
3. Measure tread depth and riser height on the bottom, middle and top step.
4. Measure stair width at the narrowest point.
5. Measure and note every landing, turn and winder separately.
6. Note the nosing profile and depth if you may wrap it.
7. Photograph the whole flight for reference when you order.

Recording measurements so nothing gets lost

Write every figure down as you take it rather than trusting memory for ten minutes — it is astonishingly easy to transpose a tread and riser number once you are back at a keyboard. A simple numbered list, step 1 through the top step, with tread and riser against each, is enough for the calculator and doubles as a record if you ever need to reorder.

What a professional measure adds

A fitter's measure typically goes further than a homeowner's: they check for square, note any dip or twist in the stringer, identify treads that will need repair before fitting, and confirm which installation style (waterfall or wrapped) the nosing profile actually supports. If your own numbers and a professional quote disagree by more than a few percent, ask why before you order material.

Measuring an already-carpeted staircase

If you are replacing an existing runner, do not simply reuse the old piece's length as your new order figure. Old carpet stretches slightly over years of use, and a worn runner may have been trimmed or repaired at some point, so its current length is not a reliable stand-in for a fresh measurement. Pull back the old runner enough to expose bare treads and measure the staircase itself using the same four-number method — tread, riser, width and step count — even though it takes a few extra minutes.

While the stairs are exposed, check the condition of the substrate. Loose treads, popped nails or old staple heads left behind from the previous fitting should be dealt with before the new runner goes down, since a rough surface telegraphs through even a good quality pile within months.

When to remeasure before reordering

It is tempting to reorder using a supplier's record of your original purchase, but remeasure if any of the following have changed: the staircase has had any carpentry work, you are switching fibre or pile height (which can change the effective nosing wrap), or more than a couple of years have passed, since older timber staircases can develop a slight seasonal movement in tread depth. A five-minute remeasure costs nothing next to the price of an order that no longer fits.

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.