Work out stair steps and riser instantly with clear inputs, formula shown and shareable results.
Riser count is the total rise divided by the preferred riser, rounded to a whole number, and the actual riser is then the rise divided by that count — all risers must be equal. Total run is one fewer going than the riser count, and pitch should stay at or below 42 degrees for a domestic stair.
Stair geometry
risers = round(total rise / preferred riser); actual riser = rise / risers; run = (risers - 1) x going
Because people step by feel, not by looking. A single odd riser is the classic trip hazard and is prohibited by building regulations.
Twice the riser plus the going should be between 550 and 700 mm. It captures the comfortable relationship between step height and depth.