Stair Calculator
Lay out a code-compliant staircase with a live diagram.
Live Layout
15 risers · 14 treadsTotal Rise is required. Add a Total Run to lock the exact geometry — otherwise the targets below size the stairs.
9' 1"
ft
in
Required — finished floor to finished floor.
Auto
ft
in
Optional — leave blank to size the run from targets.
7-1/2"
Guideline — sets how many risers the rise is divided into.
10-1/2"
Guideline — used when no Total Run is given.
1"
Finished tread stock — dropped from the bottom stringer cut.
Cut List
Number of risers
15
Actual riser height
7.267" decimal
7-1/4"
Bottom riser cut
Riser height − tread thickness (stringer drop)
6-1/4"
Number of treads
14
Actual tread depth
10.500" decimal
10-1/2"
Total run
12' 3"
Stringer length
Per stringer — measured along the slope
15' 3"
Stair angle
36.6°
Code Check — 1 issue
✓
Max riser height
Actual 7-1/4" · IRC R311.7.5 limit 7-3/4"
✓
Min tread depth
Actual 10-1/2" · IRC R311.7.5 limit 10"
✓
Riser consistency
All 15 risers equal · within the 3/8" code tolerance
!
Comfort · 2 × riser + tread
25.03" · ideal range 24"–25"
✓
Comfort · stair slope
36.6° · comfortable range 30°–37°
Recommended Tools
AffiliateCode checks reference IRC R311.7 residential limits. Always confirm against your local building code before cutting.