StairCalc: Stairway Estimator

StairCalc helps builders, contractors and DIYers lay out a straight staircase from a few measurements, in inches or millimetres.

• Enter total rise, target riser height, tread depth, stair width and nosing overhang
• Get the number of steps and treads, the actual riser height and the stair slope angle
• See the total run, the stringer length and how many stringers you need
• Check the layout against IRC, IBC, ADA or UK Part K limits, with a line-by-line report showing which item is over or short and by how much
• Compare 2 × riser + tread with the Blondel comfort guideline
• View a side-profile stringer layout drawing with rise, run and pitch angle
• Estimate handrail length and baluster count for one or both sides using the 4 in sphere rule
• Get tread and riser board counts, sizes and total board area
• Switch between inches and millimetres; entered values convert automatically
• Copy or share the results as text
• Save named stair projects with notes and reload them later

Code values are reference figures from published model codes and may differ locally; always confirm with your building authority.