Stair calculator

Divide total rise into equal risers and calculate the run for one fewer tread than risers.

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Total vertical rise

Number of risers

More inputs and assumptions

Tread going

Answer

…

Divide total rise into equal risers and calculate the run for one fewer tread than risers.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Step-by-step calculation

Inputs are substituted below. Each line evaluates the next operation; intermediate values are displayed to 12 significant digits while the calculation uses full precision.

Saved scenario

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Formula and assumptions

Rise = total rise ÷ risers; run = (risers − 1) × going. The upper floor is the final landing. No headroom, nosing, handrail, structural or local code check is performed.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Stair calculator

Divide total rise into equal risers and calculate the run for one fewer tread than risers.

Rise = total rise ÷ risers; run = (risers − 1) × going. The upper floor is the final landing. No headroom, nosing, handrail, structural or local code check is performed.

Next: Right triangle calculator

A worked example

Example inputs: total vertical rise = 280, number of risers = 16, tread going = 28. Rise per riser = 17.5.

Before you use the result

Rise = total rise ÷ risers; run = (risers − 1) × going. The upper floor is the final landing. No headroom, nosing, handrail, structural or local code check is performed.

Example results for total vertical rise

These examples use Number of risers: 16; Tread going: 28. They are reference calculations, not recommended settings.

Total vertical rise	Rise per riser
140	8.75
280	17.5
560	35

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ToolOctopus. “Stair calculator.” Updated 2026-09-26. https://tooloctopus.com/stair-calculator.

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