Measure your total rise and this calculator gives you the riser count, riser height, stringer length, a side view and top view of the steps, and a full material list, the same numbers we use on every garage steps job. All the math runs right here in your browser. Nothing gets sent anywhere.

Garage Steps Calculator

Fill in your total rise and the width across the door's brick mold. The other fields already carry our standard numbers, change them only if your job is different.

Measure from the slab where the stringers will land straight up to the finished floor inside the door (the bottom of the threshold), or to the top of the threshold if you pick that below. Finished floor not in yet? Measure to the subfloor and add its thickness.

Some inspectors, Gretna for one, measure the top riser to the top of the threshold. Measure your total rise to whichever one your inspector uses.

Closed risers in a garage are usually 3/4 inch particle board shelving, fit between the stringers flush with each riser cut.

Outside of brick mold to outside of brick mold. The outside of the stringers lines up with it, and the treads hang 1-1/2 inches past each side. Open risers over 36 inches need a third stringer. Closed risers carry 2 stringers up to 48 inches.

The run of each step.

How far the tread hangs past the riser below it.

A 2×12 laid flat is 1-1/2 inches thick.

How we build these: our max riser is 7-5/8 inch. That is our rule. The code max is 7-3/4 inch, and we keep 1/8 inch in hand because one riser cut over 7-3/4 fails inspection. Stringers get glued to the slab with PL or a similar polyurethane construction adhesive, never screwed or Tapconned into the concrete, and never with Simpson strong ties. The two stringers are joined by a 2x4 back board, and 3 inch exterior-rated framing screws or lag screws into solid house framing hold them, and the same screws hold each tread to its stringer. Open-riser treads are screwed only, not glued; closed-riser treads are glued and screwed. Stringers and treads are both 2×12, regular pine or cedar, never pressure-treated in a garage. Open stringers, no kicker plate, so dirt and dust blow through instead of collecting. The full method, including layout and the bottom-cut drop, is in How to Build Garage Steps. Open risers wider than 36 inches at the brick mold need a third stringer, see Garage Steps with 3 Stringers. Closed risers carry 2 stringers up to 48 inches. If the numbers above flag a landing, see Garage Steps with a Landing.

This calculator covers open or closed risers on 2 or more stringers. For code background, riser and tread math, and how the bottom-cut drop actually gets marked on the board, read How to Build Garage Steps start to finish before you cut anything.