Stairs Lab: Stair Calculator

Stairs Lab is a stair calculator that shows your staircase in real 3D and gives you a stringer cut sheet you can build from. Enter the floor-to-floor height and Stairs Lab works out rise and run, the number of risers and treads, stringer length, angle and headroom, then checks the stair against IRC 2021 R311.7.

EVERY STAIR LAYOUT
• Straight stairs, L-shaped and U-shaped stairs with a landing
• Winder stairs: L, U and C shaped, mono-stringer winders
• Spiral and helical stairs
• Split landings and platform steps on one, two or three sides
• Chain flights, landings, winders and ramps freely in the 3D stair system builder

READY TO CUT
• A stair calculator for every flight: rise and run, riser height and tread depth
• Stair stringer calculator: common, closed and mono stringers, stringer spacing and middle stringers for wide stairs
• Cut list for stringers, treads and risers, with riser boards on or off
• Shopping list in stock lumber sizes
• Nosing, tread depth and total-run control: set the run or let Stairs Lab size it

SAFE AND TO CODE
• Code check against IRC 2021 R311.7, with headroom and floor opening
• Balusters that never break the 4" sphere rule, railing height and layout

PLANS YOU CAN SHARE
• PDF plans with your notes, 3D model export, estimates
• Save every stair in projects and folders and edit it later, with no re-typing

WORKS YOUR WAY
• Feet-inch fractions or millimetres
• 21 languages
• Works fully offline. No ads, no account.

Whether you are building deck stairs, basement stairs or a staircase with a landing, Stairs Lab is the stair calculator that shows you exactly what to cut.