Stair calculator

Estimate outputs: Risers, Actual riser height, Tread depth. Adjust Total rise, Available horizontal run, Maximum riser height to match your project.

Inputs and units

Use the units shown beside each field. Replace the sample values with your measurements and the figures on the selected product packaging.

Formula and assumptions

Risers
ceil(Total rise / Maximum riser height)

Actual riser height
Total rise / Risers

Tread depth
Available horizontal run / max(1, Risers - 1)

ceil = round up; floor = round down; max = the greater value. Trigonometric angles are converted from degrees to radians.

Allowance is applied before rounding to whole packages. Whole units are rounded up; displayed decimals are rounded only for readability.

This is a preliminary geometry or quantity calculation, not a design check. Dimensions, spacing and performance requirements must come from your project.

Worked example

Sample values are examples, not product specifications. Run the calculation again with your own measurements.

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