Enter your Total Height and Step Run (Tread Depth), choose your Calculation Method, and the Stair Calculator works out the ideal Step Rise, Number of Risers, Total Run, Stringer Length, and Stair Angle — everything you need to plan a staircase that's safe, code-friendly, and actually fits your space.
Step Rise (Height)
--
Number of Risers
--
Total Run
--
Stringer Length
--
Stair Angle
--
Code Compliance
--
The ideal step rise height is between 6.5 and 8 inches. Building codes typically require risers to be no more than 7.75 inches high, with a maximum variation of 3/8 inch between the tallest and shortest riser in a flight of stairs.
Divide the total height by your desired step rise height. For example, if you have 84 inches of total height and want 7-inch risers, you need 12 steps (84 ÷ 7 = 12).
Most building codes require a minimum tread depth of 10 inches for exterior stairs. However, 11-12 inches is more comfortable for most people and provides better safety.
Stringer length is calculated using the Pythagorean theorem: √(total run² + total rise²). This gives you the diagonal length needed for cutting your stair stringers.
Risers are the vertical parts of stairs (step height), while treads are the horizontal parts where you step. A flight of stairs typically has one more riser than treads.
Yes, most jurisdictions have specific building codes for stairs including maximum rise height, minimum tread depth, and handrail requirements. Always check your local codes before building.
The ideal stair angle is between 30-40 degrees. Angles steeper than 40 degrees become difficult to climb, while angles less than 30 degrees take up excessive space.
For deck stairs, 2-inch thick lumber (actual 1.5 inches) is standard and meets most building codes. Thinner materials may not provide adequate support and durability.