MovePik

How to measure stairs

What to count and measure on a staircase, and how the numbers become a runner length or an area to paint.

What this guide is for

Stairs are measured differently from a room: there is no floor area to multiply out, only the same small surfaces repeated many times, so a small error on one step is repeated on every step. This guide shows what to count and measure on stairs that are already in place, and how the numbers become the length of a stair runner or the area of treads and risers to paint or varnish.

It is about materials only. It says nothing about building or altering stairs, whether they meet building rules, or how to fix a runner.

The parts you measure

  • Tread: the flat part you stand on. The tread depth runs from the back of the tread to the front of the nosing.
  • Riser: the upright part between two treads. The riser height is the rise from the top of one tread to the top of the next.
  • Nosing: the front edge of a tread, which often sticks out over the riser below.
  • Stair width: across a tread, from wall to wall or between the side boards (the strings).
  • Landing: a flat floor between two flights.

Step by step

  1. Count the treads: the steps you stand on between the bottom floor and the top floor. Neither floor is a tread, and a landing is not one either.
  2. Count the risers: the number of times you step up. On many straight flights there is one more riser than there are treads, because the last step up lands on the top floor, but count them rather than assume it.
  3. Measure the tread depth and the riser height on two or three steps and use the largest of each. Steps are meant to be even, but older or worn stairs can differ a little.
  4. For a runner, find the nosing wrap. Lay a soft tape (a sewing tape) over one step the way the runner will lie: from the back of a tread, over the nosing and down to the back of the tread below. Whatever it reads beyond the tread depth plus the riser height is the length the runner needs to go round the nosing. If it reads no more than that, enter 0.
  5. For paint or varnish, measure the stair width where the finish goes.
  6. Measure each landing the runner crosses, along the runner, and include the length it needs over the landing’s front edge: the nosing wrap is only counted on treads.
  7. Write it down on a sketch of the stairs, flight by flight, before you shop.

Worked example: a runner for a straight flight

A straight flight with 13 treads and 14 risers. The treads are 10 1/2 in deep and the risers 7 1/4 in high. A soft tape laid over one step reads 19 1/4 in, so the nosing wrap is 19.25 − 10.5 − 7.25 = 1.5 in. The runner is sold by the foot.

  • Treads: 13 × (10.5 + 1.5) = 156 in
  • Risers: 14 × 7.25 = 101.5 in
  • Runner: 156 + 101.5 = 257.5 in, which is 21.46 ft
  • Rounded up to whole feet: 22 ft, with 6.5 in left over

The planner starts a runner with no allowance. With 10% the same flight needs 23.6 ft, so 24 ft. If the runner’s instructions call for extra length at the top or the bottom, add it as a landing line or as extra length.

Stair rods and pads are counted per step. With one rod per riser (the planner also offers one per tread) that is 14 rods (4 packs with 2 spare, if they come in packs of 4), and one pad per tread is 13 pads.

Worked example: a flight with a landing, in metric

A straight stair with a landing halfway: 6 treads, the landing, 6 more treads, and 14 risers in all. The treads are 25 cm deep, the risers 19 cm high and the nosing wrap is 2 cm. The runner covers 90 cm across the landing and 2 cm over its front edge, so the landing line is 92 cm.

  • Treads: 12 × (25 + 2) = 324 cm
  • Risers: 14 × 19 = 266 cm
  • Landing: 92 cm
  • Runner: 324 + 266 + 92 = 682 cm, or 6.82 m
  • Sold in steps of 0.1 m: 6.9 m, 8 cm left over. Sold in steps of 0.5 m: 7.0 m, 18 cm left over.

Worked example: painted risers and varnished treads

Back to the first flight, which is 36 in wide. In the paint calculator, the stairs helper under Painted areas in step 1 turns the counts and sizes into two rows:

  • Treads: 13 × 36 in × 10.5 in = 4,914 sq in, or 34.13 sq ft
  • Risers: 14 × 36 in × 7.25 in = 3,654 sq in, or 25.38 sq ft

The risers get paint, two coats, at an example coverage of 350 sq ft per gallon: 25.375 × 2 ÷ 350 = 0.145 gal, or 0.16 gal with a 10% allowance. One quart (0.25 gal) covers it; a one-gallon can would leave about 0.84 gal.

The treads get a clear floor varnish, with the number of coats from its label (three in this example) and an example coverage of 500 sq ft per gallon: 34.125 × 3 ÷ 500 = 0.205 gal, or 0.23 gal with the allowance, so also one quart. Coverage figures are per coat, as paint coverage and coats explains; use the ones on your own cans.

On stairs the can size often matters more than the coverage, because the amounts are small. The two rows do not include the strings, skirt boards or balusters: add those as more rows. Keep the stairs out of use until the finish has dried as its label says, and ask the maker about the slip resistance of the finish on the treads.

Common mistakes

  • Counting step-ups as treads. Entering 14 treads instead of 13 in the first example adds one tread and one nosing wrap, 12 in, and the runner becomes 269.5 in: 23 ft instead of 22 ft. The step-ups are the risers.
  • Leaving out the nosing wrap. Without it, the first flight comes to 13 × 10.5 + 101.5 = 238 in, rounded up to 20 ft. That is 240 in of runner for stairs that need 257.5 in: 17.5 in short.
  • Counting a landing as a tread. In the metric example, 13 treads and no landing line give 617 cm, so 6.2 m, 62 cm less than the 6.82 m the stairs need. A landing is its own line, measured along the runner.

Two flights, one runner

If the same runner goes on two flights, enter both as lines of one runner: their lengths are added before rounding. Two flights like the first example need 2 × 257.5 = 515 in, which is 42.92 ft, so 43 ft; rounded flight by flight they would need 22 + 22 = 44 ft. That saving is only real if you cut both pieces from one length yourself. If the store cuts each piece to size, buy each flight’s length on its own. How pack rounding works explains why amounts are added before they are rounded up.

What this guide does not cover

Winders, curved and spiral stairs, a runner’s pattern repeat, fixing the runner, and the slip resistance of a runner or a finish: follow the instructions of the runner, rod, pad and finish makers. For outdoor steps, use the deck, fence and patio stain calculator. For the walls of the hall and the landing, measure them like a room, as how to measure a room shows.

Frequently asked questions

Where do I enter a stair runner in the planner?

In step 2 of the flooring calculator or the room refresh planner: Add stair runner, type the step the store sells it in under Sold in steps of, then add a stair runner line with the treads, risers, tread depth, riser height, nosing wrap and any landings. A stairs entry with only a runner line needs no floor size or wall height. If you already used the stairs helper of the paint section in step 1, Use the treads and risers from step 1 copies its counts and sizes.

Does the runner width change the length to buy?

No. A runner is counted by its length in the width you choose, so the width you type is only a label for the shopping list. Measure the stair width to choose that width; for paint, the stair width is what turns the counts into areas.

My stairs turn a corner. Can I still use this?

A flat landing, yes: add the length the runner covers across it as a landing. Winders (tapered steps in the turn) and curved or spiral stairs are not covered, because the planner counts every tread the same; have the runner supplier measure those parts.

Last updated:

Related pages