Stair Stringer Calculator
Enter the rise and run to calculate the diagonal stringer length and the number of stringers you need.
Results
- Stringer length
- 169.01 in (14.08 ft)
- Total run
- 130 in
- Stringers needed
- 4
Estimates only. Round up and buy a little extra to account for waste, spills, and breakage.
Enter the rise and run to calculate the diagonal stringer length and the number of stringers you need.
How to use the stair stringer calculator
- Enter the total rise in in.
- Enter the number of steps.
- Enter the tread depth in in.
- Enter the stair width in in.
- Optionally add a price to estimate the total project cost.
- Read your quantities instantly — no sign-up, and you can print the estimate to take to the supplier.
Worked example
Inputs
- Total rise
- 108 in
- Number of steps
- 14
- Tread depth
- 10 in
- Stair width
- 36 in
Results
- Stringer length
- 169.01 in (14.08 ft)
- Total run
- 130 in
- Stringers needed
- 4
Using the example values above, the stair stringer calculator returns 169.01 in (14.08 ft) (stringer length). Change any field to match your own project and the numbers update instantly.
Formula
Stringer length = √(total rise² + total run²). Use one stringer every ~16 in of stair width plus one.
Frequently asked questions
- How far apart should stair stringers be?
- Space stringers no more than 16 in on center for 5/4 treads, 12 in for heavier loads.
- What size lumber for stringers?
- Use 2×12 lumber so enough material remains after notching.
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