Stair Rise & Run
Work out step rise, run and stringer length for stairs.
About Stair Rise & Run
Dividing total rise by a comfortable per-step rise gives the step count, then rises evenly divide the total. The stringer length is the hypotenuse spanning total rise and total run. Stairs need consistent rise and run so each step feels identical, and the stringer must be cut to the true diagonal length.
Formula
Stair Rise & Run
Steps = total rise / target rise; stringer = sqrt(rise^2 + run^2)
- stringer
- The angled support board of the stair
Worked example
With the default values below, Stair Rise & Run returns Number of Steps of 15. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Total rise
- 108 in
- Target rise per stepminimum 1 in
- 7.5 in
- Run per stepminimum 1 in
- 10.5 in
Results
- Number of Steps
- 15
- Actual Rise per Step
- 7.20 in
- Stringer Length
- 15.2 ft
Step by step
- 1Values used
- 2Stair Rise & Run
- 3Number of Steps= 15
- 4Actual Rise per Step= 7.20 in
- 5Stringer Length= 15.2 ft
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Stair Rise & Run calculated?
Steps = total rise / target rise; stringer = sqrt(rise^2 + run^2) Dividing total rise by a comfortable per-step rise gives the step count, then rises evenly divide the total. The stringer length is the hypotenuse spanning total rise and total run.
Why does Stair Rise & Run matter?
Stairs need consistent rise and run so each step feels identical, and the stringer must be cut to the true diagonal length.
What values do I need to enter?
This calculator takes 3 inputs: Total rise, Target rise per step, Run per step. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.