Work out staircase design instantly with clear inputs, formula shown and shareable results.
The number of risers must divide the floor height exactly, so the preferred riser is used only to find the nearest whole count and the actual riser follows from dividing back. There is always one fewer tread than riser. The classic comfort rule is that twice the riser plus the going should fall between 550 and 700 mm.
Riser count
Risers = round(floor height / preferred riser); actual riser = floor height / risers
Comfort rule
2 x riser + going should be 550 to 700 mm; total going = (risers - 1) x tread
Preliminary estimate only. Stair geometry, headroom, handrails and guarding must comply with the building code adopted locally.
Risers = round(floor height / preferred riser); actual riser = floor height / risers. The number of risers must divide the floor height exactly, so the preferred riser is used only to find the nearest whole count and the actual riser follows from dividing back.
No. Codes require all risers in a flight to be equal within a few millimetres because an uneven riser is a serious trip hazard, particularly on descent.
This calculator takes 4 inputs: Floor to floor height, Preferred riser height, Tread going, Stair width. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.