Calculate equal stair risers, treads, horizontal run, angle, stringer length, and traditional stair proportions from floor-to-floor rise.
The calculator rounds the total rise divided by your target or maximum riser height upward to a whole riser count, then divides the rise evenly so every calculated riser is equal.
A standard single flight uses one fewer tread than risers because the upper finished floor normally serves as the final walking surface.
ceiling(total rise ÷ target riser height)total rise ÷ riser countriser count − 1tread count × horizontal going per treadatan(total rise ÷ total run), in degrees√(total rise² + total run²)2 × actual riser + tread goingFor 108 in total rise, a 7.5 in maximum riser rounds up to 15 risers. Each riser is 7.2 in; 14 treads at 10 in create 140 in of run, an angle of about 37.65°, and a stringer length of about 176.82 in.
For 2.8 m total rise and a 0.19 m target, 15 risers are about 0.186667 m each. Fourteen 0.28 m treads create a 3.92 m run; the implementation calculates the corresponding angle and stringer.
Available-run mode keeps the same riser calculation but divides the supplied horizontal space equally among the calculated treads.
Measure vertically between finished floor levels, accounting for final floor finishes.
Enter horizontal travel per tread. Do not substitute the tread board depth or nosing projection.
Choose dimensions from the requirements applicable to your jurisdiction, building type, and stair system.
Rounding the riser count upward keeps actual riser height at or below the entered target. Construction layout must keep finished risers uniform.
When horizontal space is fixed, the calculator divides available run by tread count. This reports resulting going and angle; it does not declare that geometry acceptable.
Angle uses the shared rise/run angle helper. Stringer length is the right-triangle hypotenuse between total rise and run; actual cut length, bearing, overhangs, and connections require project-specific layout.
Twice the actual riser plus tread going is a traditional proportion reference. The displayed value is informational and is not evaluated against a universal acceptable range.
Requirements differ by country, jurisdiction, occupancy, building type, and whether work is new or existing. This calculator does not estimate headroom, landings, guards, handrails, structural capacity, openings, or code approval.
Divide total rise by your chosen maximum riser height and round upward.
Divide total rise evenly by the whole-number riser count.
For a standard flight between floors, the upper floor serves as the final walking surface.
Multiply tread count by horizontal going per tread.
The calculator takes the arctangent of total rise divided by total run.
It is the hypotenuse of the total-rise and total-run right triangle.
It is a traditional relationship using twice riser height plus tread going, shown without a compliance judgment.
Going is the horizontal distance traveled from one step to the next, distinct from nosing projection.
Yes. Available-run mode calculates the resulting equal tread going for the available horizontal distance.
No. Verify every dimension and detail with applicable local requirements and qualified professionals.
Yes. Metric input supports millimeters, centimeters, and meters through the shared conversion system.
No. Headroom requires additional floor, ceiling, opening, and layout geometry.