Choose a count, then check actual riser height
A total rise rarely divides evenly into a preferred riser height. Count mode rounds the riser count upward, then actual-height mode divides the same total rise among the chosen count. For a simple flight meeting an upper landing, tread count is one fewer than riser count.
Measure and calculate
- Measure the finished vertical rise.
- Enter a target maximum riser and calculate the required whole riser count.
- Use the chosen count to inspect actual riser height and the separate tread-based run estimate.
Risers = ceiling(total rise ÷ target maximum riser height).
A worked example
- Inputs
- The total rise is 28 in and the target maximum is 7 in.
- Calculation
Ceiling(28 ÷ 7) = 4 risers. Actual height: 28 ÷ 4 = 7 in. Three 11 in treads give a 33 in run.- Result
- 4 riser
The initial result is 4 risers. The geometry does not resolve landings, nosings, foundations or local stair requirements.
Read the result
| Output or check | What it means for your project |
|---|---|
| Whole risers | The total finished rise is divided by the target maximum riser height and rounded upward. |
| Actual rise and horizontal run | Actual riser height uses the chosen whole count. Run mode uses one fewer tread than risers; confirm that this convention matches the landing arrangement. |
Common questions
Why is tread count one fewer than riser count?
In this simple model, the upper landing completes the last rise. A different arrangement needs a layout-specific count.
Should I round each riser height independently?
The actual-height mode divides the full rise by the count. Independently rounding repeated risers can prevent the flight from meeting the intended total rise.