Enter your total rise and this tool returns a code-checked stair layout: step count, exact riser height, total run, stringer length, and cut angle. Works in imperial or metric. Checked against IRC R311.7 limits (compatible with Ontario Building Code 9.8 private stairs).
This tool gives estimates for planning purposes only and isn’t a substitute for professional measurement, a site inspection, or your local building code and supplier guidance. Always verify quantities and code requirements before purchasing materials or beginning work.
Stair layout starts from one measurement: the total rise, the exact vertical distance from finished floor to finished floor (or grade to deck surface). The number of risers is the total rise divided by your maximum allowed riser height, rounded up. Dividing total rise by that count gives the actual riser height — every riser identical, which is both a code requirement (variation under 3/8 in / 9.5 mm) and the difference between stairs that feel right and stairs people trip on.
Worked example: a deck 108 in above grade, max riser 7.75 in: 108 ÷ 7.75 = 13.9 → 14 risers. Actual riser: 108 ÷ 14 = 7.71 in. With 10-in treads and a flush mount, total run = 13 × 10 = 130 in, and the stringer is √(108² + 130²) ≈ 169 in — so you're cutting from 16-ft 2×12 stock.
Codes vary by jurisdiction and edition; commercial and egress stairs have different limits. Confirm requirements with your local building department before cutting.
Under the IRC (US), the maximum riser height is 7 3/4 inches (197 mm). Ontario's Building Code allows up to 200 mm for private stairs. This calculator flags any layout exceeding 7 3/4 in / 197 mm so it passes in both jurisdictions.
The IRC requires a minimum tread depth of 10 inches (254 mm) measured nosing to nosing. Deeper treads (10 1/2 – 11 in) are more comfortable and are required in some jurisdictions for main stairs.
Divide the total rise (floor-to-floor height) by your maximum allowed riser height, then round up to the next whole number. Divide total rise by that step count to get the actual, uniform riser height. Risers must not vary by more than 3/8 inch within a flight.
A comfort guideline: twice the riser height plus the tread depth should land between 24 and 25 inches (roughly 610–635 mm). Layouts outside that band feel awkwardly steep or shallow even when they pass code.
The stringer length is the hypotenuse of total rise and total run — this calculator reports it. Buy the next stock length up (stringers are typically cut from 2×12) and account for the top connection detail before cutting.