Work out the number of steps, riser height, run and stringer length for a staircase.
Calculated instantly in your browser.
How do you calculate stairs for a staircase?
Steps = round(total rise ÷ target riser), riser height = total rise ÷ steps, and stringer = √(rise² + run²). Even risers are essential for safety. For example, a 112-inch total rise with a 7-inch target gives 16 steps of exactly 7 inches each. Many codes cap risers near 7.75 inches — always check local rules.
Understanding your result
Even risers are essential for safety. Many codes limit risers to about 7.75 inches and require treads of at least 10 inches — always check local rules.
Formula and method
Steps = round(total rise ÷ target riser). Riser height = total rise ÷ steps. Stringer = √(rise² + run²).
Assumptions and limitations
The results come from the total rise you enter and a target riser, and assume a straight flight. Building codes for riser and tread limits, headroom, handrails and landings vary by location, so always check local rules. It does not design winders, curved stairs or structural support, and it is not a substitute for approved plans.
Worked example
A 112-inch total rise with a 7-inch target gives 16 steps of exactly 7 inches each.
How to use this tool
- Enter the total rise (floor to floor).
- Set a target riser height and tread depth.
- Press Calculate.
About the Stair Calculator
The Stair Calculator turns a total floor-to-floor rise into a step count with even riser heights, the total run and the stringer length you’ll need to cut.
Who should use this tool
DIY builders, carpenters and renovators laying out a staircase who need a step count, even riser height, total run and stringer length before cutting timber. Useful for decks, basements and loft conversions where getting the geometry right matters for safety.
Benefits
- Calculates step count and even riser height
- Gives the total run and stringer length to cut
- Helps keep every riser the same for safety
- Free browser tool, useful during planning
Practical use cases
- Planning a straight flight for a deck or basement
- Working out riser height from a total rise
- Finding the stringer length before cutting timber
- Checking a staircase layout against a target riser
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Frequently asked questions
What is a comfortable stair angle?
Roughly 30–37°, which a ~7-inch riser with a ~11-inch tread produces. Steeper stairs are harder and less safe.
Why must every riser be the same height?
Uneven risers are a trip hazard because people quickly get used to a consistent step and misjudge one that differs. Dividing the total rise into equal risers keeps the flight predictable and safe, which is why building codes require it. This tool spreads the rise evenly across whole steps for you.
Do I need to check building codes?
Yes, always. Codes set limits on riser height, tread depth, headroom, handrails and landings, and these vary by region and by whether the stair is interior or exterior. Use the calculator to plan the geometry, then confirm every figure against your local rules before building.