TOOL 14 / FREE · NO SIGNUP
Stair Rise & Run Calculator
Plan equal risers and tread count for one straight flight. Compare the required run with your available space.
Worked example loaded. These are example measurements and product assumptions.
THE METHOD
How to use this estimate
- Measure between the two finished-floor elevations. Enter your own riser target and horizontal going.
- The upper floor or landing provides the final tread, so this model has one fewer tread than risers.
- After counting risers, their equal height is recalculated. The repeated-step angle differs from the whole-flight envelope angle.
risers = ceil(total rise / chosen riser target); equal riser = total rise / risers; treads = risers − 1; run = treads × going
A worked example
The “Load worked example” button uses the same inputs as this example. Explicit unit suffixes keep their meaning in either unit system.
- Finished-floor total rise
- 2.7 m
- Your target maximum riser
- 180 mm
- Horizontal going per tread
- 250 mm
- Available horizontal run
- 4 m
- Treads below the upper landing
- 14
- Equal actual riser height
- 180 mm / 7.087 in
- Horizontal going per tread
- 250 mm / 9.843 in
- Total horizontal run
- 3.5 m / 11.483 ft
- Repeated-step angle (degrees)
- 35.754
- Rise/run layout diagonal — not a stringer cut length
- 4.42 m / 14.503 ft
- Available minus required horizontal run
- 0.5 m / 1.64 ft
Questions, answered
Why does the riser height change?
A whole riser count is chosen first. Total rise is divided equally across that count so actual rise fits the entered target.
Can I use this as a stringer cut list?
No. Finish thickness, nosing, tread thickness, support and notches are outside this geometry estimate.
Sources and product assumptions
These references explain units or product specifications. Your selected product label takes priority; none of these sources endorses this calculator.
Source check: 4 October 2026. Worked examples use stated, editable assumptions.