Calculate rise, run, number of steps, stringer length, and headroom for any staircase.
Step 1: Measure the total rise – the vertical distance from finished floor to finished floor.
Step 2: Enter your desired tread depth (the flat part you step on). Standard is 10–11 inches (254–279 mm).
Step 3: Optionally enter the available headroom to verify it meets code minimums (80 inches / 2032 mm).
Step 4: Review the results. The calculator uses the comfort rule: Riser + Tread should equal 17–18" (imperial) or 2×Riser + Tread ≈ 600–640 mm (metric).
Stringer length is calculated as the hypotenuse of the total rise and total run triangle.
Most building codes specify a maximum riser height of 7¾ inches (196 mm). The comfortable range is 6–8 inches (150–200 mm). A 7-inch (178 mm) riser is considered ideal.
The 7-11 rule states that risers should be about 7 inches and treads at least 11 inches. Combined with the comfort formula (R + T = 17–18"), this produces comfortable, safe stairs.
Stringer length is the hypotenuse of the right triangle formed by total rise and total run. Use the Pythagorean theorem: stringer = √(rise² + run²).
Most building codes require a minimum of 6 feet 8 inches (80 inches / 2032 mm) of headroom measured vertically from the stair nosing to the ceiling above.