Stair Stringer Calculator
Riser/tread layout and stringer length from total rise — verify local code before you cut. Click any i for detail.
Stairs
Total rise (in)
i
Rise
Floor-to-floor height in inches. |
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|---|---|
Target riser (in)
i
Riser
Preferred riser height; the page rounds to a whole number of risers. |
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Target tread (in)
i
Tread
Going depth per tread (not including nosing quirks). |
How to use this calculator
- Measure total rise carefully.
- Enter preferred riser and tread depths.
- Read riser count, actual riser height, run, stringer length, and angle.
Results explained
The page picks the nearest whole number of risers so actual riser height ≈ total rise / risers. Treads are usually one fewer than risers. Total run ≈ treads × tread depth, and stringer length is the hypotenuse of rise and run. Building codes cap riser height and require consistency — this is a layout sketch, not an engineered stamp.
Quick reference: stair layout
risers = round(total_rise / target_riser); run ≈ (risers − 1) × tread.
| Item | Detail |
|---|---|
| Common riser | About 7–7¾ in residential (confirm code) |
| Common tread | About 10–11 in going |
| Treads | Usually risers − 1 |
| Stringer | √(rise² + run²) |
Always verify local stair codes and headroom before cutting stringers.
How the estimate is built
risers = round(rise / target_riser); actual = rise / risers; run = (risers−1)×tread; stringer = √(rise²+run²).
Example scenario
100 in rise, ~7 in target → 14 risers at ~7.14 in, 13 treads, run and stringer from tread depth.
FAQ
Do I include finished floor thickness?
Yes — total rise should be finished floor to finished floor, or you will be short/long after flooring.
What about nosing?
Nosing adds to tread depth in some code definitions. This page uses the going depth you enter; check how your code measures tread.
Why is my riser over 7¾ in?
Try a different riser count (change the target so rounding lands elsewhere) or adjust the opening. Codes often cap risers.
Is the stringer length exact for cutting?
It is the geometric hypotenuse. Account for material thickness, landing details, and manufacturer patterns.