6XC

Stair Calculator (Rise & Run)

Step count, riser height and tread depth from total rise — checked against the comfort rule and typical code limits.

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The Geometry of a Comfortable Stair

Divide total rise by an ideal riser (~17.5 cm / 7 in) and round to a whole step count — every riser must then be identical: uneven risers are the #1 trip cause. The classic comfort check is 2 × riser + tread = 60-65 cm (24-25.5 in): a 17.5 cm riser pairs with a 27-30 cm tread. Typical residential code limits: riser ≤ 19-20 cm, tread ≥ 25 cm — the tool flags violations.

Total run = tread × (steps − 1); if the space is short, options are a landing with a turn, a steeper (still legal) riser, or winders — in that order of comfort. Headroom needs ~2 m over the walk line.

Frequently Asked Questions

Why is my staircase tiring even though it fits code?

Probably the 2R+T sum drifting from 63 cm — legal-but-steep 19/23 stairs sum to 61 yet feel harsh. Aim for the middle of the comfort band, not the code edge.

Do all steps really have to be equal?

Yes — codes typically allow only ~1 cm variation between risers. Feet memorize the rhythm after two steps; one odd riser breaks it, usually at the worst moment.

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