Stair Calculator
Work out steps, riser height, total run and pitch for a staircase.
A design guide. Building codes set limits on riser, tread and pitch — always check the regulations that apply where you are.
Dividing the rise into equal steps
A staircase climbs a fixed floor-to-floor height. The job is to split that into a whole number of equal risers close to a comfortable target, then set the tread depth to give a safe, usable pitch.
steps = round(rise ÷ target riser) · riser = rise ÷ steps · run = (steps − 1) × tread
Because risers must all match, the target you enter is only a starting point — the calculator rounds to a whole number of steps and reports the exact riser height that results.
A 280 cm floor-to-floor rise with a target riser near 18 cm gives 16 steps at 17.5 cm each, 15 treads, a 375 cm run at a 25 cm going, and a pitch of about 35°.
Comfortable, safe stairs
Good stairs feel effortless because their proportions suit a natural stride. A classic rule of thumb pairs riser and tread so that two risers plus one tread land around 60–64 cm. Steeper or shallower than the comfort band quickly feels wrong underfoot.
Worth remembering
- Equal risers, always. Uneven steps are a trip hazard and usually fail inspection.
- Mind the run. The total horizontal length must fit the space available.
- Check the code. Local regulations govern limits and headroom.