The Builder Calc is a free staircase planning tool. You enter the total rise and the tread depth you want, and it works out the number of risers, the riser height, the run and the stringer. It checks the result against the International Residential Code, shows the stair in 3D, and gives you dimensioned drawings you can print: the side profile, a stringer layout, and a tread detail with a cut list.
It does not replace a building inspector, an engineer or your own measurements on site. It gives estimates for planning. Local codes differ and are updated, so confirm the rules that apply to your project with your local building department before you cut anything.
Today the calculator covers straight-run stairs. L-shaped, U-shaped and spiral stairs are planned, followed by different materials and a one-click PDF export. Guides on stair comfort, code and construction are published alongside the tool.
Found a mistake in a calculation or a guide, or have a request? Write to contact@thebuildercalc.com. Corrections are welcome and are taken seriously.