Turn a total rise into equal risers, treads, total run, stringer length, stair angle, and estimated stringer count.
Measure the finished vertical rise from the lower walking surface to the upper finished surface.
risers = ceiling(total rise ÷ target riser)actual riser = total rise ÷ riserstreads = risers − 1stringer line = √(total rise² + total run²)Total run equals tread depth multiplied by the tread count. Stringer count uses the entered maximum spacing across the stair width.
Stairs are safety-critical. Before cutting, verify local requirements and approved plans for rise and run limits, uniformity, nosing, landings, headroom, guards, handrails, stringer material, remaining wood at notches, support, and fastening. This planning calculator does not certify a stair or size structural members.
Risersceiling(105 ÷ 7.5) = 14 risers at exactly 7.5 in each
Treads14 − 1 = 13 treads
Total run13 × 10 = 130 in, or 10.83 ft
Stringer line√(105² + 130²) = 167.1 in, or 13.93 ft
In a typical stair that ends at an upper floor or deck, that upper surface acts as the final landing. The calculator therefore counts one fewer horizontal tread than vertical risers. Construction details can differ, so compare the calculated layout with the actual top and bottom connections before cutting stock.
The diagonal stringer line also is not the board length. The board needs enough material beyond that line for bearing, attachment, end cuts, and any unnotched sections required by the design.