Stair type

Stair runner length calculator for winder stairs

Winders are the pie-shaped treads that turn a corner without a landing. They are the hardest part of any runner job because each one is wider at the outside edge and almost nothing at the inside.

Calculate the straight steps normally, then add a winder allowance per turning tread. Be honest about the limits: winders are usually a template-and-fit job, not a tape-measure job.

Your staircase

Start from typical stair sizes where you live

IRC-style stairs: 10 in minimum tread, 7¾ in maximum riser. Runners are usually 27 in or 32 in wide and sold by the linear foot.

Number of stairs

Count every step you will cover.

Tread depth (in)

Front edge to back of the step. Fractions like 10 1/2 work.

Riser height (in)

The vertical face between two treads.

Waste allowance

Custom%

10% is a common starting point; pattern matching and winders need more.

Add a nosing / overhang allowance per step

Needed when the runner wraps around a projecting nose (Hollywood installs and thick pads). Waterfall installs usually don't need it.

Your stair runner length

20 ft 3.1 in

Total runner required for 13 steps, including a 10% waste allowance.

Total runner length in each unit
Inches	243.1 in
Feet	20.26 ft
Feet & inches	20 ft 3.1 in
Yards	6.75 yd
Meters	6.17 m
Centimeters	617.47 cm

Recommended purchase length

21 ft

7 yd · 6.4 m · 252 in

This calculator provides an estimate based on the measurements and installation assumptions you enter. Complex, curved or winder staircases may require professional measurement.

Your measurements, drawn to scale

Side elevation of a staircase. The runner travels across each tread and down each riser, so every step consumes tread depth plus riser height of material.

How to allow for a winder tread

Measure the depth along the line the runner will follow — commonly the centre line of the runner, not the wall. On a typical three-tread winder set, each winder consumes 1.5 to 2 times the depth of a straight tread along its outer edge.

Cut per step, not per flight

Most fitters cut winders as individual pieces so the leading edge stays parallel to the nosing. That means extra cut ends, extra binding and considerably more waste — 20% is not unreasonable.

Where the calculator stops

This tool gives a defensible estimate for the straight portion and flags winders as an approximation. For a firm quantity on a winder set, template the treads in cardboard or have your fitter measure them.

Questions people ask

How much extra runner do winder stairs need?: Allow roughly 1.5 to 2 times a straight tread per winder along the runner's path, and increase your waste allowance to 15 to 20%.
Can a runner be fitted over winders?: Yes, but usually as individually cut and bound pieces rather than one continuous length. It is a job for an experienced fitter.

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