How the Stair Calculator Works
The tool divides the total rise by the target riser height and rounds up to a whole number of risers. It then divides the total rise evenly across those risers and estimates the horizontal run using one fewer tread than risers, assuming the upper floor forms the final walking surface.
Formula and method
Number of risers = ceiling(total rise ÷ target riser height). Actual riser height = total rise ÷ number of risers. Tread count = risers − 1. Total run = tread count × tread depth.
Tips for better estimates
Measure finished floor to finished floor and consider the intended floor finishes. Use the computed actual riser height when laying out the staircase, not only the target value.
Important limitations
This is a preliminary geometry aid, not a building-code compliance tool. Verify local rules for riser height, tread depth, nosings, headroom, landings, handrails, guards, and allowed variation before building.