Stair Stringer Calculator
Work out stair stringer layout, rise, run and number of steps from total height, ideal for framing and deck stairs, free in your browser.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the total rise (floor to floor) and your preferred riser height.
- Optionally add the total run for the tread depth.
How it works
Steps = total rise ÷ preferred riser, rounded to a whole number; the actual riser is the total rise ÷ steps.
Worked example
2700 mm rise, 180 mm target. 15 risers at 180 mm, 14 treads.
Common mistakes
- Uneven last step — all risers must be equal, so the actual riser rarely equals your target exactly.
- Ignoring code limits on riser height and tread depth.
Frequently asked questions
How do I calculate stair stringers?
From the total rise and run, the tool divides the rise into equal risers, sets the matching going, and gives the stringer length and notch layout.
What is a comfortable stair rise and going?
Around 170–190 mm rise with a 250–280 mm going suits most stairs; check the building code that applies where you are.
Is this code-compliant?
It's a planning aid only — always check riser/tread limits in your local building code before building.
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Cite this tool
Zerdly. (2026). Stair Stringer Calculator. Retrieved from https://www.zerdly.com/tools/stair-stringer-calculator/
Tip: Enter any known values to calculate the remaining results.
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