Stair Calculator
Calculates rise, run, number of steps, stringer dimensions, and building code compliance
Total vertical height from bottom to top
Target height for each riser step
Horizontal depth of each tread
Total number of riser steps needed
Adjusted height per riser for even spacing
Total number of treads (risers minus one)
Total horizontal distance of the staircase
Diagonal length of the stair stringer
Frequently Asked Questions
What is the ideal riser height for stairs?
Building codes typically require risers between 4 and 7.75 inches, with 7 to 7.5 inches being the most comfortable range. Risers should be uniform; uneven riser heights are a common cause of trips and falls.
What is the standard tread depth?
The IRC requires a minimum tread depth of 10 inches. Most comfortable stairs have treads between 10 and 11.25 inches. A deeper tread feels safer but requires more horizontal space for the staircase.
How do I calculate stringer length?
Stringer length is the hypotenuse of a right triangle formed by the total rise and total run. Use the Pythagorean theorem: stringer = square root of (total rise squared plus total run squared). Add extra length for cuts at top and bottom.
What is the 7-11 rule for stairs?
The 7-11 rule is a common guideline stating that risers should be about 7 inches and treads about 11 inches. Another rule is that riser plus tread should equal 17-18 inches. These proportions produce the most comfortable stride.
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