Stair calculator

Type the floor-to-floor height. You get the number of risers, the rise and going, the pitch and the length of the flight, each checked against Approved Document K.

Worked example

How the sum works

The calculator uses the fewest risers that keep each rise within the limit for the stair (220 mm for a private stair in a house), so each one is the total rise divided by the number of risers. If you don't give a going, it picks one inside the allowed range that keeps 2 × rise + going between 550 and 700 mm and, for a private stair, the pitch at 42° or less.

The Part K limits it checks

From Approved Document K table 1.1: a private stair takes a rise of 150 to 220 mm and a going of 220 to 300 mm, with a pitch of no more than 42°. Utility stairs take 150 to 190 mm and 250 to 400 mm, and general access stairs 150 to 170 mm and 250 to 400 mm. Every stair has 2 × rise + going between 550 and 700 mm.

It also checks the number of risers in a flight. The full rules cover headroom, handrails, guarding, landings and winders too: see the guide.