Measuring runner for enclosed stairs

A box stair is closed on both sides — walls or full stringers — so there is no exposed edge to design around. The length calculation is the same as a straight flight, but the width decision changes.

Measure wall to wall at the narrowest point, because plaster is rarely parallel.

Your staircase

Optional starting measurements

Example measurements only, not building-code advice. Replace them with measurements from your own stairs.

Check a few steps before using one set of measurements for the whole flight.

Number of stairs

Count the tread-and-riser pairs the runner will cover. Exclude landings.

Tread depth (in)

Measure the runner path across the flat tread. Fractions like 10 1/2 work.

Riser height (in)

The vertical face between two treads.

Waste allowance

Custom%

10% is the starting allowance here, not a guarantee. Ask your fitter about patterns and turns.

Add a nosing / overhang allowance per step

Enter the extra runner path around the edge, including any underside wrap. Do not add it twice if it is already included in your measurements.

Your runner estimate

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

Length to order

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.

One step, shown in profile

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.

Length is straightforward

Steps × (tread + riser), plus nosing and waste. Box stairs are almost always uniform, so a single tread measurement checked against two others is enough.

Width and reveal on a closed stair

You can either fit a runner with a deliberate reveal each side or fit wall-to-wall carpet. If you want a runner look, measure the narrowest point and subtract at least 6 in total so the runner clears the plaster all the way up.

No binding on the wall side?

Both long edges are still visible on a runner, so both still need binding or serging. Only a full wall-to-wall fit escapes that.

Questions people ask

What width runner for a box staircase?: Measure wall to wall at the narrowest point and subtract 6 to 10 in total so you keep an even reveal even where the walls are out of square.
Is the length calculation different for box stairs?: No. Length is steps × (tread + riser) plus allowances, exactly as for an open straight flight.

Related guides

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