Stair Calculator
Calculate the number of steps, rise per step, and run per step for a staircase from total rise height.
How to use this tool
- Enter the total vertical rise (floor-to-floor height) in inches.
- Enter your target rise per step (7 to 7.75 inches per code).
- Enter the desired tread run (10+ inches per code).
- The calculator returns exact step count, actual rise, and total horizontal run.
Design a code-compliant staircase by calculating step count, rise, and total run.
Formula
Steps = round(total rise (in) ÷ desired rise per step (in))
Actual rise per step (in) = total rise ÷ steps
Total run (in) = steps × run per step (in)
How it works
This calculator designs a straight staircase from three inputs: total vertical rise, a target riser height, and the desired tread depth (run). The number of steps is found by dividing the total rise by the desired rise and rounding to the nearest whole number so all risers are equal. The actual riser height is then back-calculated by dividing the total rise by that whole number of steps, and the total horizontal footprint (run) is the step count multiplied by the tread depth. IRC residential code typically requires risers between 4 and 7¾ inches and treads of at least 10 inches; always verify the actual rise against local building code.
Worked example
Worked example
- Total rise = 108 in; desired rise per step = 7.5 in.
- Steps = round(108 ÷ 7.5) = round(14.4) = 14 steps.
- Actual rise = 108 ÷ 14 ≈ 7.71 in per step.
- Total run = 14 × 10 in = 140 in.
The staircase has 14 steps, each with an actual rise of approximately 7.71 in, and a total horizontal run of 140 in.
Key terms
- Rise
- The vertical height of a single stair step; IRC residential code limits risers to 4–7¾ inches.
- Run (tread depth)
- The horizontal depth of a single stair tread; IRC requires a minimum of 10 inches for residential stairs.
- Total rise
- The full vertical distance from finished floor to finished floor (or finished floor to landing) that the staircase must climb.
- Total run
- The total horizontal distance the staircase occupies on the floor plan, equal to the number of steps multiplied by the tread depth.
- 7-11 rule
- A common design guideline where riser height plus tread depth should sum to approximately 17–18 inches for comfortable stair climbing.
Frequently asked questions
- How do I calculate stair rise and run?
- Divide the total vertical rise by your target rise per step to get the number of steps (round to nearest whole number). Then recalculate: actual rise = total rise ÷ steps.
- What is the code for stair rise and run?
- IRC building code requires a maximum rise of 7-3/4 inches and minimum run (tread depth) of 10 inches per step. Check local codes as they may vary.