Stair Calculator
Lay out a safe, even staircase. Enter your total rise (floor to floor) and target riser height to get the number of risers and treads, the exact riser height, the total run, and the stringer length to cut.
Your project
Estimate
Number of risers (steps)
- Actual riser height
- 7.2in
- Number of treads
- 4treads
- Total run
- 44in
- Stringer length
- 56.9in
Estimates are guidance only and exclude tax, labor, and site conditions unless stated. Confirm with a local pro.
How it's calculated
No black boxes — here is the exact math behind your estimate, so you can check it or adapt it for your own quote.
- 1
Number of risers = round( total rise ÷ target riser height ) - 2
Actual riser height = total rise ÷ number of risers - 3
Number of treads = number of risers − 1 - 4
Total run = number of treads × tread depth - 5
Stringer length = √( total rise² + total run² )
Worked example
A 36-inch total rise with a 7.5" target riser and 11" treads.
Inputs
- Total rise
- 36 in
- Target riser height
- 7.5 in
- Tread depth
- 11 in
Result
- Number of risers (steps)
- 5 risers
- Actual riser height
- 7.2 in
- Number of treads
- 4 treads
- Total run
- 44 in
- Stringer length
- 56.9 in
Tools & materials for this project
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- Stair stringer brackets Attach treads to stringers without notching.
- Framing square Lay out rise and run accurately.
- Stair gauges Clamp to the square for repeatable step layout.
Compare local pros for stairs
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