Stair Calculator
Plan equal risers, treads, total run, stair angle, and theoretical stringer line.
What this calculator does
The riser count rounds up; total rise is then divided equally.
Rise and run
Measure finished-floor to finished-floor. Riser count rounds up so equal actual risers do not exceed the target.
Your plan updates instantly
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Riser count rounds up from the target, then total rise is divided equally.
The arithmetic uses the exact values shown above. Verify field measurements, product pack sizes, layout constraints, and local requirements before ordering or building.
How to interpret the result
The riser count rounds up; total rise is then divided equally.
How the result is calculated
Risers = ceil(total rise ÷ target riser); treads = risers - 1.
Worked example
A 108 in rise at 7.25 in target produces 15 equal 7.2 in risers.
Practical guidance
- Measure the project at least twice before ordering.
- Use actual product dimensions and package coverage.
- Keep a saved or printed copy of the inputs used for the estimate.
Assumptions and limitations
This is geometry, not code approval or structural stringer design.
Methodology
Calculations use standard geometry and normalized units. Countable products are rounded up where partial products cannot normally be purchased.
Read the complete calculation methodology and testing policy.
Frequently asked questions
Are results rounded for purchasing?
Countable materials and packages are rounded up. Measured area, length, volume, and cost remain decimal values where appropriate.
Is this a final construction specification?
No. It is a transparent planning estimate. Verify product instructions, site conditions, plans, and local requirements.