Straight stair calculator with live plans
Enter the finished floor-to-floor height and the horizontal space available for a straight stair. StairEditor proposes a step count, then updates the side, top, and isometric views while you refine the design.
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Best for
- • Open rooms with enough continuous run
- • Basement and loft access
- • Checking an existing straight-flight proposal
Measurements to take
- • Finished floor-to-floor height
- • Maximum horizontal flight length
- • Flight width
- • Stairwell opening and floor thickness
Results you get
- • Suggested number of steps
- • Riser height and going
- • Pitch and Blondel value
- • Estimated minimum headroom
- • Live 2D, isometric, and parts views
Example with numbers
Worked example: a comfortable straight stair
A 2,800 mm floor height divided into 16 equal risers produces a balanced starting point. The final design still depends on the measured opening and site conditions.
Starting measurements
- • Floor-to-floor height: 2,800 mm
- • Available run: 4,200 mm
- • Width: 900 mm
Starting result
- • 16 risers at 175 mm
- • 15 goings at 280 mm
- • Blondel value: 630 mm
- • Pitch: about 32°
Illustrative example only: verify the opening, headroom, structure, and applicable rules before building.
What to have reviewed
Straight stairs get the most detailed PDF StairEditor currently produces, including individual tread information. Confirm structure, joinery, local rules, and site measurements with a qualified professional before cutting material.
Guides for this calculation
Take the right measurements and check what limits the plan before you finalize your stair.
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.
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.
Common questions
What measurements do I need?
Start with finished floor-to-floor height and the maximum horizontal run. Stair width and opening dimensions improve the headroom review.
Does the calculator choose the step count?
Yes. Auto mode proposes a step count from the geometry and Blondel target. You can switch to a manual count to compare alternatives.