Stair Calculator

Calculate number of steps, riser height, tread depth, total run, and stringer length for staircases based on total rise.

Floor-to-floor height

Ideal: 7-7.75 in

Min 10 in (IRC code)

Steps
Riser Height
"
Total Run
"
Stringer
"

Formulas

Number of Steps = Total Rise ÷ Target Riser Height
Actual Riser = Total Rise ÷ Number of Steps
Total Run = (Steps - 1) × Tread Depth
Stringer = √(Total Rise² + Total Run²)

FAQ

The IRC (International Residential Code) allows a maximum riser height of 7¾ inches and a minimum of 4 inches. Most comfortable stairs fall between 7 and 7½ inches.
A common guideline: risers should be about 7 inches and treads about 11 inches. More precisely, the sum of two risers plus one tread should equal 24-25 inches for comfort.

Pro Tip

Measure total rise from finished floor to finished floor, including any flooring material thickness. Even a small error multiplied across many steps creates noticeable unevenness.

IRC Code Reference

Max riser height7.75 in
Min tread depth10 in
Min width36 in
Min headroom6 ft 8 in

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