Calculyn

Stair Calculator

Work out the number of steps, riser height and tread depth for a staircase.

in
in
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Results update as you type.

Number of risers

15steps

Within typical US residential code (≤ 7¾″ riser, ≥ 10″ tread)

Actual riser height
7.2in
Number of treads
14
Total run
140in
Stringer length
176.8in
Stair angle
35.8°
Number of risers15

Estimate only — confirm dimensions against your local building code.

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Quick answer

A 108″ rise with 7.5″ target risers needs 15 risers of 7.2″ and 14 treads — a total run of 140″ at 10″ treads.

How it works

Divide the total rise by your target riser height and round up to get the number of steps, then spread the rise evenly so every step is the same height.

Formula

Risers = ⌈rise ÷ target riser⌉ · Treads = risers − 1 · Run = treads × tread depth

Assumptions & limitations

  • Results are rounded for display.

Frequently asked questions

What's a comfortable stair?

A common rule is riser × 2 + tread ≈ 25″. For example, 7.25″ risers with 10.5″ treads.