Engineering / Browser calculator

Stair Calculator

Stair Calculator works from the inputs you provide and returns risers, actual riser (cm), treads, horizontal run (cm). Use the calculation panel to explore a scenario, then check the formula and limitations before applying the result.

Your inputs

Minimum: 1e-06
Minimum: 1e-06
Minimum: 1e-06

Your results

Enter your values and calculate to see the result.

Estimates depend on the stated method and entered quantities. Check applicable standards before using a result for a real-world design or safety decision.

Formula and calculation method

Risers = ceil(total rise / desired riser). Actual rise = total rise / risers. Treads before top landing = risers − 1.

Geometric estimate only; local building codes govern safe dimensions and construction.

How to use stair calculator

  1. Set Total rise (cm). The example below uses 280.
  2. Set Desired riser (cm). The example below uses 17.5.
  3. Set Tread depth (cm). The example below uses 28.
  4. Select Calculate to update the result. Reset restores the illustrated inputs. Copy, print or download your own result if you need a record.

Worked example

Example inputs
Total rise (cm)
280
Desired riser (cm)
17.5
Tread depth (cm)
28
Risers
16
Actual riser (cm)
17.5
Treads
15
Horizontal run (cm)
420

Factors affecting your result

Geometric estimate only; local building codes govern safe dimensions and construction.

Changing total rise (cm) changes the scenario being evaluated. Adjust one input at a time when comparing results, keep a copy of the assumptions, and compare values using the same unit and period. A precise arithmetic result does not make an uncertain assumption precise.

Frequently asked questions

How does the stair calculator work?

Risers = ceil(total rise / desired riser). Actual rise = total rise / risers. Treads before top landing = risers − 1.

What inputs does Stair Calculator need?

Enter total rise (cm), desired riser (cm), tread depth (cm). Choose values that correspond to the same situation and measurement convention.

How should I interpret the stair calculator result?

Geometric estimate only; local building codes govern safe dimensions and construction.

Are my stair calculator inputs uploaded?

No. The calculation runs in this browser. Favorites, recent tool names, theme and formatting preferences may be saved locally, but calculation inputs are not sent to a calculation server or stored by this website. Shared links do not include entered values.

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