Stair Rise Run
Calculator
Results
- Number of risers
- 16
- Actual riser height (mm)
- 175
- Number of treads
- 15
- Total horizontal run (mm)
- 3,750
- Stair angle (degrees)
- 34.99202
Construction results
| Number of risers | 16 |
| Actual riser height (mm) | 175 |
| Number of treads | 15 |
| Total horizontal run (mm) | 3,750 |
| Stair angle (degrees) | 34.99202 |
formula-map diagram
- Number of risers
- 16
- Actual riser height (mm)
- 175
- Number of treads
- 15
- Total horizontal run (mm)
- 3,750
- Stair angle (degrees)
- 34.99202
Formula breakdown
Formula
risers = round(total rise ÷ target riser); riser = total rise ÷ risers= 16
Note
Simplified model: results are quantity estimates only. They ignore openings, overlaps, cuts, site conditions and local building codes. Structural figures are not a substitute for a design by a qualified engineer.
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See all →Frequently asked questions
What do 'rise' and 'run' mean for a staircase?+
Rise is the vertical height of each individual step, and run is the horizontal depth of each step's tread. Together they define the stair's proportions and how comfortable and safe it is to climb.
How does the calculator determine the number of steps and their exact rise?+
It divides the total vertical height to be climbed by a target rise (commonly aiming for 7-7.75 inches per step) to get an approximate step count, rounds to a whole number, then divides the total height by that whole number to get the exact, evenly-sized rise for every step.
Why is it critical that every step have the same rise?+
Uneven rise heights are a leading cause of trips and falls on stairs, since people unconsciously expect each step to match the height of the previous one — building codes strictly limit the allowable variation between the largest and smallest rise in a single staircase, often to a fraction of an inch.
Is there a standard formula relating rise and run for comfortable stairs?+
A widely used guideline is that 2× rise + run should fall between about 24 and 25 inches (sometimes stated as rise + run ≈ 17-18 inches), which balances a comfortable stride — steeper stairs (higher rise, shorter run) feel cramped, while shallow stairs (low rise, long run) take up excessive space and can feel awkward to walk.
Does the calculator account for the thickness of finished flooring or treads?+
The core rise/run math is based on structural floor-to-floor height, but you should account for finished floor thickness (both the level you're leaving and arriving at) when translating the calculated rise into actual framing dimensions, since finished flooring added later effectively changes the first and last step's rise if not planned for up front.