Stair Calculator

About this calculator

This calculator plans a staircase by dividing the total rise (floor-to-floor height) by a maximum comfortable riser height — commonly capped around 7 inches (178 mm) under residential building codes — rounding up to a whole number of steps, then recomputing the actual riser height = total rise ÷ number of steps so every riser comes out identical. Most codes require riser heights to be uniform within about ⅜ inch (10 mm) throughout a flight, since inconsistent risers are a leading cause of stair-related trips and falls.

Carpenters, general contractors, and DIY builders use this calculation before cutting a single stringer, and architects use it early in a floor plan to confirm a staircase will fit within the available floor-to-floor height and horizontal run while staying code-compliant. Enter the total rise to get the step count and exact riser height.