Stair Calculator

Going is measured nosing to nosing, which is what the 2R + G comfort rule uses. The tread board you cut is that figure plus the nosing.

Code check

• Riser height 500 mm is outside the usual 100–196 mm range.
• Going (tread depth) 250 mm is outside the usual 254–330 mm range.
• 2R + G = 1250 mm is outside the comfortable 550–700 mm band.
• Pitch of 64.0° is steeper than the 42° limit.
• Headroom at the opening edge is -20300 mm, below the 2032 mm you asked for. Move the opening edge back to 8750 mm from the bottom riser or less.

The ranges used here (riser 100–196 mm, going 254–330 mm, 2R + G 550–700 mm, 6 ft 8 in headroom, pitch under 42°) match the IRC/IBC and most European codes, but every jurisdiction words it differently and some add a maximum of 18 risers between landings. Check your local code before you cut timber.

Scaled cross-section

The flight, the floor above, the stairwell opening edge and the headroom that results — all drawn to the same scale.

About this tool

It divides the floor-to-floor rise into equal risers, keeps treads one fewer than risers as a straight flight requires, and reports the real riser and going — then checks them, the 2R + G comfort rule, the pitch and the headroom against common building-code limits. Headroom is measured from the nosing to the underside of the floor above, taking the floor thickness into account, and the tool tells you how far up the run the stairwell opening may start. Everything runs in your browser; nothing is uploaded.