Stair math starts with the total rise divided into equal risers, with treads following from the run. Our stair calculator returns riser height, tread depth, the number of steps, and the stringer length, and it checks every result against IRC R311.7 limits (maximum 7¾-inch riser, minimum 10-inch tread) so your layout is code-ready.
The complete How to Calculate Stairs guide walks through Blondel's comfort rule, stringer geometry, landings, winders, and guardrails, and the stairs FAQ answers 100 common code and layout questions.