Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Riser height (in)
7.20
Number of risers
15
Number of treads
14
Total run (in)
147.0
Stringer length (in)
182.4
Stair angle (degrees)
36.3
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter total rise (floor to floor) (in).
- 2Enter target riser height (in).
- 3Enter tread depth (in).
- 4Read your riser height (in) on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Most codes cap riser height around 7.75 in and require at least a 10 in tread. Dividing total rise by 7 gets you close to a legal, comfortable stair.
Worked example
Using the values the calculator loads with:
Inputs
- Total rise (floor to floor): 108 in
- Target riser height: 7 in
- Tread depth: 10.5 in
Results
- Riser height (in): 7.2
- Number of risers: 15
- Number of treads: 14
- Total run (in): 147
- Stringer length (in): 182.4
- Stair angle (degrees): 36.3
What each field means
Inputs
- Total rise (floor to floor) (in)
- The total rise (floor to floor) used in the calculation, measured in in. Starts at 108 in so you have a working example on load.
- Target riser height (in)
- The target riser height used in the calculation, measured in in. Starts at 7 in so you have a working example on load. Accepted range: 4–8 in.
- Tread depth (in)
- The tread depth used in the calculation, measured in in. Starts at 10.5 in so you have a working example on load. Accepted range: 9–14 in.
Results
- Riser height (in)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Number of risers
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Number of treads
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total run (in)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Stringer length (in)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Stair angle (degrees)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the stair rise, run & stringer calculator work?
Most codes cap riser height around 7.75 in and require at least a 10 in tread. Dividing total rise by 7 gets you close to a legal, comfortable stair. The underlying maths is: Risers = round(total rise ÷ target riser); stringer = √(rise² + run²).
What do I need to enter?
3 values: total rise (floor to floor), target riser height, and tread depth. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the riser height (in) result mean?
It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Stair Stringer Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/stair-stringer
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/stair-stringer" target="_blank" rel="noopener">Stair Stringer Calculator — RevenueLab</a> (2026).</p>
Source: [Stair Stringer Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/stair-stringer) (2026).