Formula
How the stair estimate works
- Riser count = total rise ÷ target riser height, rounded to the nearest practical whole number
- Actual riser height = total rise ÷ riser count
- Tread count = riser count − 1; total run = tread count × tread depth
Free project planning tool
Stair calculator
Plan stair risers, actual rise, tread count, total run, stringer length, and tread cost.
✓ Metric & imperial✓ Transparent assumptions✓ No signup
Risers & treadsInstant estimate
Example calculation
A floor-to-floor rise of 108 in with a target 7.25 in riser produces 15 risers at 7.2 in each, 14 treads, and a 140 in total run using 10 in treads.
Planning tips
- Measure finished-floor to finished-floor height, not rough framing alone.
- Verify maximum riser height, minimum tread depth, headroom, landings, and handrails locally.
- Use the result for planning only; structural stringer layout should be checked professionally.
Common questions
Stair calculator FAQ
How many treads are in a staircase?
A typical straight stair between two floors has one fewer tread than risers because the upper floor acts as the final tread.
What is a comfortable stair rise?
Comfort and legal limits vary. Many residential stairs are near 7–7.75 in per riser, but local requirements control.
Can I use this to cut stringers?
Use it as a planning check only. Material size, bearing, notches, landings, code, and structural loading require project-specific verification.