Staircase calculators
Pick a tool. The calculators run in your browser and need no account.
Stair project planner
Everything for one stair on one page — code check, stringer cuts, floor opening, cut list and scaled drawings. Sign up free to save projects.
Fit a stair into a space
Height fixed by the building, run fixed by the hallway — every riser and tread combination that fits, ranked, or a straight answer that none does.
Stair calculator
Floor-to-floor height in; risers, treads, run, pitch, stringer, cut list and a code check out. Start here.
Cut a stringer from a 2×12
The saw-side calculator: framing-square settings, both cut angles in degrees, the throat check, the bottom drop, boards to buy and a numbered cut sequence.
Floor opening & headroom
How long the hole in the floor has to be for the stair to clear the headroom — and which tread sits under its edge.
Baluster spacing
Count and the exact marks from the newel face, inside the 4″ sphere rule or the UK 100mm rule.
Angle & pitch
Degrees, rise:run ratio and percentage slope, with the comfortable and legal bands marked.
Area & perimeter of any shape →
Squares to ellipses, trapezoids, regular polygons, L-shapes and any outline by its corner points — with the working shown and a drawing.
Coming next
Winder and tapered-tread geometry measured on the walk line; spiral stair treads and headroom per turn; landing and multi-flight layouts, which is what the fit calculator sends you to when a straight run will not go; timber, concrete and carpet takeoffs. If one of those is what you came for, tell us — it moves up the queue.