How is the number of risers chosen?

Total rise divided by the target riser, rounded to the nearest whole number, and at least one.

Two risers plus one going. Many Australian stair guides look for 700–750 mm. This page reports the number; it does not pass or fail the stair.

Does this meet the building code?

No. Riser and going limits differ by place. Check the numbers against the code that applies to the stair.

Stair Stringer Calculator

Risers, goings, and stringer length for a total rise — geometry, not a code certificate.

Risers, goings, and a stringer length for a total rise. This is geometry so you can cut a stringer to try — it is not a building-code certificate.

Measure

Total rise

Floor to floor.Target riser

Often around 170–180 mm.Going

Tread depth, nosing aside.

Stringer length

4.62 m

15 risers of 180 mm and 14 treads of 250 mm. 2R+G is 610 mm — outside the 700–750 mm band many Australian guides use.

Risers: 15 × 180 mm
Treads: 14
2R+G: 610 mm

Not a certified stair design. Check the code that applies before you build.
Stringer length is the hypotenuse of one riser and going, times the number of risers.

Stringer4.62 m

Measurements stay in this browser. Nothing is uploaded.

Worked example

A total rise of 2,700 mm with a target riser of 175 mm gives 15 risers of 180 mm and 14 treads. At a 250 mm going, 2R+G is 610 mm — outside the 700–750 mm band many Australian guides use — and the stringer is about 4.62 m.

FAQ

How is the number of risers chosen?: Total rise divided by the target riser, rounded to the nearest whole number, and at least one.
What is 2R+G?: Two risers plus one going. Many Australian stair guides look for 700–750 mm. This page reports the number; it does not pass or fail the stair.
Does this meet the building code?: No. Riser and going limits differ by place. Check the numbers against the code that applies to the stair.