Stair calculations
How to calculate stair rise and run
Work out stair riser height, going, pitch and total run from your floor-to-floor height, with the typical ranges to aim for before you build.
Start with the total rise
Measure from finished floor to finished floor. That figure is the total rise, and it is the first number you need to calculate stair rise and run. Every riser takes an equal share of it, so the split has to come out even enough for the stair to stay comfortable.
For a typical house stair, divide the total rise by a target riser height of 170 to 185 mm, then round to a whole number of risers.
Work out the going
The going is the horizontal depth you walk on, measured from one nosing to the next. Once you have the riser count, pick a going that fits the run you have and still feels natural underfoot.
A short going can make a stair feel steep even when the riser height looks fine, so check rise and run together.
Check the pitch
Pitch is the angle of the stair. Most everyday stairs feel comfortable at roughly 30 to 35 degrees. Steeper stairs get harder to use day after day.
Try a few step counts in the editor. A small change often improves comfort without moving the stairwell much.
Put this into practice
Open the editor and test these numbers on your own staircase, with live drawings and a comfort score. No account needed.
Related guides
Comfort
Using the Blondel formula for comfortable stairs
What the Blondel formula (2h + g) measures, why the target sits near 600 to 640 mm, and how to use it to balance riser height and tread depth.
Planning
Stair headroom: what to check before building
How stair headroom depends on the floor opening, slab thickness and finishes, and the layout mistakes that cause clearance problems near the top of a flight.
Layouts
Straight vs quarter-turn stairs: choosing a layout
Straight or quarter-turn stairs? Compare footprint, landings, comfort and circulation to pick the layout that fits a compact room or a corner.