Remodelers
Staircase Calculator
Calculate riser height, tread depth, number of steps, and total run for code-compliant stairs.
108" total rise / 14 risers = 7.71" per riser. 13 treads at 10.5" = 11.4 ft total run. Riser + tread = 18.2" (comfort range is 17-18"). IRC limits: max riser 7.75", min tread 10", min width 36". All risers must be within 3/8" of each other.
Common Questions
What is the building code for stair riser height?
IRC building code allows a maximum riser height of 7 3/4 inches. Most comfortable stairs have risers between 7 and 7.5 inches. All risers in a staircase must be within 3/8 inch of each other.
How do I calculate the number of stairs I need?
Measure the total rise from finished floor to finished floor in inches. Divide by your target riser height (7 to 7.5 inches is ideal). Round to the nearest whole number. The number of treads is one less than the number of risers.
What is the minimum tread depth for stairs?
IRC code requires a minimum tread depth of 10 inches, not counting the nosing. A 10 to 11 inch tread with a 1 inch nosing is standard for residential stairs.
How do I calculate stringer length?
Use the Pythagorean theorem. The stringer length equals the square root of (total rise squared plus total run squared). This calculator does the math and gives you the cut length.
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