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Stair Calculator

Use this stair calculator entirely in your browser.

ResultLayout: 16 risers and 15 treads

Actual riser height: 175.00 mm

Total horizontal run: 3.750 m

Calculated pitch: 34.99°

Planning geometry only; compare every dimension with the requirements that apply at the project location.

Calculations happen locally in your browser.

How to use this calculator

  1. Enter the labelled values and review the live result.
  2. Review the live result and use Copy result when you need to share it.

How the calculation works

The riser count is rounded up from total rise divided by the target maximum riser, then the actual riser, run, and pitch are calculated.

Formula

Risers = max(2, ceil(total rise ÷ target riser)); actual riser = total rise ÷ risers; run = (risers − 1) × tread depth

Step-by-step calculation

  1. Enter the labelled values and review the live result.
  2. The riser count is rounded up from total rise divided by the target maximum riser, then the actual riser, run, and pitch are calculated.
  3. Check the displayed result, then copy it if needed.

Worked example

A 2,800 mm rise with a 175 mm target and 250 mm treads produces 16 risers, 15 treads, and a 3.75 m run.

Risk guidance

What the stair calculation includes

The result divides the total vertical rise into equal risers, reports one fewer tread than risers for a typical floor-to-floor flight, and uses tread depth to estimate horizontal run and pitch. It does not calculate landings, nosings, headroom, width, guards, handrails, structure, or accessibility.

Use a locally verified target

Maximum riser height, minimum going or tread depth, permitted pitch, measurement conventions, and tolerances vary. Obtain the current requirements for the project location and building use before choosing the target values.

Measure the complete rise

Measure from finished lower floor level to finished upper floor level. Changes to floor finishes can alter the total rise and create unequal steps, so final construction dimensions should be checked on site by a qualified person.

Frequently asked questions

Does this stair result prove code compliance?

No. It calculates limited geometry from your inputs. Verify current local requirements and have the complete stair design reviewed by appropriately qualified people.

Why is the tread count one less than the riser count?

For a typical floor-to-floor flight, the upper finished floor acts as the final landing, so the number of treads in the flight is commonly one fewer than the number of rises. Confirm the convention for your design.

Does this tool send my inputs anywhere?

No. The interactive calculation runs in your browser and this site does not submit tool inputs to a backend.

How should I use the result?

Use it for early planning only. Verify measurements, definitions, current local requirements, and the complete design with the relevant authority and appropriately qualified professionals.

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