Formula and input notes
Risers = ceil(total rise ÷ target riser); actual riser = total rise ÷ risers; total run = (risers − 1) × tread depth
| Input | Practical note |
|---|---|
| Target riser height | This is a planning target used only to choose a whole riser count; the calculator then recomputes the equal actual riser height. |
| Tread depth | This is the horizontal depth assigned to each tread in the run calculation; confirm how nosing is treated in the governing layout convention. |
Worked stair carpet example
Stair Carpet Calculator example: ceil(77.8 in ÷ 7.25 in) = 11 risers. Each actual riser is 7.07 in; 10 treads at 10 in create 100 in of run and a 126.7-in diagonal.
Turn area into a material list
Use the square-foot result as an area check, then have the installer create a strip and roll-direction takeoff for the selected carpet.
Layout details outside the area formula
Nosing wrap, waterfall versus cap-and-band installation, landings, winders, pattern match, roll width, seams, and waste affect carpet length.
Questions specific to this calculation
Does tread-plus-riser area equal carpet roll length?
No. The displayed surface area is a geometric reference. Roll width, pile direction, seams, pattern repeat, waterfall versus cap-and-band installation, nosing wrap, landings, and winders determine the actual cut plan.
Why does the calculator first solve stair geometry?
Riser count, actual riser height, tread count, tread depth, and width determine the exposed tread-and-riser surface. The result helps describe the flight before a carpet layout is made.