/// Answer-first planning notes
What stair geometry follows from my total rise and target riser?
| Planning input | Calculation role | Check before ordering |
|---|---|---|
| Total rise | Sets the vertical distance | Measure finished-floor to finished-floor |
| Target riser | Determines a whole riser count | Compare actual riser with approved criteria |
| Tread depth | Produces run and stringer geometry | Treat nosing and landing details separately |
Unit switching preserves physical stair geometry through the exact 0.3048-meter international-foot conversion.
Evidence: National Institute of Standards and Technology/// Formula & field notes
How this stair estimate works
FormulaRisers = total rise ÷ target riser, rounded up to a whole riser. Actual riser = total rise ÷ risers. Treads = risers − 1. Stringer = √(rise² + run²).
Worked example
A 105 in total rise with a 7.5 in target produces 14 risers at 7.5 in and 13 treads.
/// Source trail
Data & assumptions
Every source has a declared scope. A reference can support a conversion or product assumption without turning this estimate into a supplier quote.
Exact international-foot to meter conversion; U.S. survey-foot conversion is explicitly outside this claim.
Effective 2025-08-18 · Reviewed 2026-07-15 · Next review 2027-07-15Independent confirmation that one international foot equals exactly 0.3048 meters; U.S. survey-foot conversion remains distinct.
Effective 2025-06-10 · Reviewed 2026-07-15 · Next review 2027-07-15/// Common questions
Stair calculator FAQ
Is this calculator code compliant?
It provides geometry only. Code requirements vary by jurisdiction and occupancy, so a qualified professional or local official must verify the final stair design.
Why are there fewer treads than risers?
In a typical floor-to-floor stair, the upper floor acts as the final walking surface, leaving one fewer constructed tread than risers.
What does stringer length include?
The result is the straight geometric slope from total rise and total run. It does not add bearing cuts, overhang, landing details, or stock-selection allowance.