Rise in. Every riser, every tread, and the layout marks.

A stair is one division and one decision: how many risers. Get the count wrong and the last step is an inch off, which everyone who ever walks it will feel. This does the division for every count, checks each against code, and hands you the square settings.

WHAT IT DOES

• Riser height and tread depth for every plausible count, from the rise and either the run you have or the 2R + T comfort rule
• Code checks: max riser, min tread, pitch, headroom and stringer throat for US IRC, UK Part K and Canada NBC, or your own limits
• Headroom under the stairwell opening, and the opening length needed to pass
• Stringer layout: framing-square settings, run minus riser board, bottom drop equal to the tread thickness, tip-to-tip length, stock length and number of stringers by width
• Throat check for a 2×12 with the fix when it is thin
• Drawn side profile with the opening and headroom line
• Landing split for an L or U stair with both flights and the footprint
• Materials list: stringers, treads, risers, fixings
• Inches with sixteenths, or millimetres

Who it's for

Deck and basement stair builders, and anyone about to cut a 16-foot 2×12 and wanting to be sure first.

What you get

• The calculator (one .html file, runs in any browser, offline)
• A 2-page quick-start guide

Good to know

• One file. No install, no account, no subscription, no internet needed after download.
• Your data stays on your computer. Export a backup any time; import it on another machine.
• Works on Mac, Windows, Linux and iPad (open the file in Safari or Chrome).
• Instant download.

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