About this calculator
Lay out a straight flight: the number of risers, exact riser height, total run, angle and stringer length, checked against the National Building Code of Canada rules for stairs in houses.
How it’s calculated
Risers = ceil(total rise ÷ maximum riser). Exact riser = total rise ÷ risers. Treads = risers − 1. Run = treads × tread depth. Stringer ≈ √(rise² + (run + one tread)²).
National Building Code of Canada 2020 (Part 9), stairs within a house: rise 125–200 mm (about 5" to 7⅞"), run 255–355 mm (10" to 14"), width at least 860 mm (2' 10"), headroom at least 1950 mm (6' 5"), and no more than 3.7 m of rise in one flight. Provinces adopt these with their own changes, so check yours.
Worked example
With these inputs:
- Total rise (floor to floor)
- 108 in
- Maximum riser height
- 7.875 in
- Run (tread depth)
- 10.5 in
- Nosing overhang
- 1 in
- Stair width
- 36 in
the result is:
- Risers
- 14 risers @ 7-11/16"
- Total run
- 11' 4-1/2"
- Stair angle
- 36.3°
- Stringer length (approx.)
- 15' 2-7/16"
- Tread board depth (with nosing)
- 11-1/2"
Tips from the trade
- Measure the total rise to the finished floor at both ends, not to the subfloor.
- Treat this as a layout check. Local code and the inspector have the final say.
- For stairs wider than 36", add a middle stringer.
Common questions
How many steps for a 9 ft rise?
108" ÷ 7⅞" = 13.7, so 14 risers at 7.71" (196 mm), inside the 200 mm limit. With a 10½" run, that’s 13 treads and a total run of about 11 ft 4 in.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the building code adopted in your province before ordering.