Stair Stringer Calculator
Lay out a staircase (riser count and height, tread depth, total run, stringer length, and angle) from the total rise, with code-range checks. Calculates in your browser.
Stringer length
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Show the math
Risers divide the rise; the stringer is the hypotenuse of rise and run:
risers = round(total rise ÷ target riser)
stringer = √(total rise² + total run²)
Most codes cap risers near 7.75 in and call for treads of at least 10 in. Values outside the 6–8 in riser and 9–11 in tread ranges are flagged. Verify against your local code. All math runs locally in your browser.
What this does
A stair stringer calculator lays out a staircase (riser count and height, tread depth, total run, stringer length, and angle) from the total rise, with code-range checks.
How to use it
- Enter the total rise.
- Set a target riser height.
- Set the tread depth.
- Read the layout and stringer length.
How it works
The riser count is the total rise divided by a comfortable riser, and the stringer is the hypotenuse of rise and run. Most codes cap risers near 7.75 inches.
stringer = √(rise² + run²)
Understanding your result
The layout is checked against common code ranges, and consistency is the safety point: people climb stairs on autopilot, so even a small variation between riser heights is a genuine trip hazard. Keep every riser and tread equal, confirm the headroom above the run, and verify the final dimensions against your local building code before cutting.
Example
A 9-ft total rise gives about 15 risers at 7.2 inches each.
Sources & methodology
Last updated .
Frequently asked questions
What is a comfortable riser height?
Most codes cap risers around 7.75 inches; 7–7.5 inches feels comfortable. The tool flags risers outside the 6–8 inch range.
How deep should a tread be?
A tread depth (run) of 10–11 inches is typical and comfortable; many codes require at least 10 inches. Below 9 inches is flagged.
How is the stringer length found?
It is the hypotenuse of the total rise and total run (√(rise² + run²)) which is the length of board to cut.
Is anything stored?
No. Everything is calculated locally in your browser.
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