Formula Used
Riser count = total rise ÷ preferred riser height. The calculator rounds this value by your selected rounding method.
Actual riser height = total rise ÷ final riser count.
Tread count = riser count - 1 for a common straight stair layout.
Total run = tread count × tread run.
Pitch angle = arctan(actual riser height ÷ tread run).
Stringer length = square root of total rise squared plus total run squared.
Comfort value = two times actual rise plus tread run.
How to Use This Calculator
Measure the finished floor height from the lower level to the upper level. Enter that value as total rise. Add your preferred riser height and tread run. Then enter nosing, landing depth, width, headroom, and local checking limits.
Press the calculate button. The result appears below the header and above the form. Review the riser count, actual riser height, total run, pitch angle, stringer length, and warning checks. Adjust values until the layout fits your space and rules.
Staircase Rise Run Planning Guide
A stair layout looks simple on paper. It becomes sensitive when one measurement changes. Total rise sets the whole job. Tread run sets walking comfort. The calculator joins both values and shows the effect before lumber is marked.
Good stairs feel regular from bottom to top. Every riser should match. Even a small uneven step can feel unsafe. For that reason, the tool divides total rise by a practical riser count. It then returns the exact riser height needed for the full opening.
Run is just as important. A deeper run gives more foot space. It also increases total horizontal space. A shallow run saves room but can feel steep. The pitch angle shows this balance. Most comfortable residential stairs sit in a moderate range, not too flat and not too sharp.
Stringer length helps with material planning. It is the diagonal distance along the stair slope. The value is useful when selecting boards and checking available stock length. The calculator also estimates tread count, total run, landing footprint, and walking surface after nosing.
Nosing is not the same as run. Run is the horizontal distance between riser faces. Nosing is the small projection beyond the riser below. It can improve foot placement, but it should follow the local rule used for the project.
Always verify the final plan against local building rules. Codes can differ by country, city, building type, and occupancy. Some projects need permits or inspections. This tool helps with layout and estimating. It does not replace an approved stair detail.
Use the result as a planning worksheet. Adjust the preferred riser, tread run, landing depth, and limits. Compare several layouts before cutting. A small change can reduce steepness, improve comfort, or make the stair fit the available opening.
Measure finished surfaces whenever possible. Use the finished lower floor and the finished upper floor. Do not measure from rough framing unless finish thickness is already included. Mark one test stringer first. Check the first tread, last tread, and landing line. Then transfer the pattern to other boards. Careful checking saves material and avoids a stair that climbs correctly but meets the floor poorly. It makes final installation cleaner and more predictable overall.
FAQs
What is total rise?
Total rise is the vertical distance from the finished lower floor to the finished upper floor. It controls the final number of risers and the actual riser height.
What is stair run?
Stair run is the horizontal distance of one tread. Total run is found by multiplying tread count by the selected tread run.
Why is tread count often one less than riser count?
The upper floor usually acts as the final walking surface. Because of that, a straight stair commonly has one fewer tread than risers.
What is the comfort formula?
The comfort formula is two risers plus one run. Many builders use it to compare whether a stair feels natural when walking.
Does this calculator replace local code?
No. It helps with layout and estimating. Always check local building rules, permits, inspections, and project requirements before cutting or building stairs.
What is stringer length?
Stringer length is the diagonal slope length from the bottom of the stair to the top. It helps estimate board length before cutting.
What does nosing mean?
Nosing is the tread projection beyond the riser below. It can increase the walking surface, but it should match the rule used for the project.
Why does the calculator show warnings?
Warnings compare your result with the limits entered in the form. They help identify steep, shallow, tight, or uncomfortable layouts before construction begins.