Stair Stringer Calculator (Rise and Run)

How to do it

1. 1
   Step 1: Open Stair Stringer Calculator (Rise and Run) and add your input

   Type your numbers or text, add your file, or pick the options you need. Nothing is uploaded: everything stays in your browser.

2. 2
   Step 2: What Stair Stringer Calculator (Rise and Run) does

   Work out the number of risers, riser height, treads and stringer length for a staircase.

3. 3
   Step 3: Read the result and compare

   The result appears at once. Change one value to see how the answer moves, then keep the figure that fits your case.

4. 4
   Step 4: Copy or save it

   Copy the result or download it. For an important decision, confirm it with the official source or an adviser.

About this tool

Enter the total rise from floor to floor in inches, the tread depth you want and the maximum riser height. The calculator gives the number of risers and treads, the exact riser height, the total run, the stringer length and the angle, and checks the IRC limits.

Steps

Number of risers = total rise ÷ maximum riser height, rounded up. Exact riser = total rise ÷ risers. There is one fewer tread than risers. Total run = treads × tread depth. Stringer length = √(rise² + run²).

Code limits (IRC)

The maximum riser height is 7¾ inches and the minimum tread depth 10 inches. Risers in one flight should not differ by more than ⅜ inch. A common comfort rule is that two risers plus one tread should be 24 to 25 inches.

Build

Mark the stringers carefully; cut the bottom to allow for the thickness of the tread so the first and last steps are equal.

Worked example

A total rise of 108 inches with a 10 inch tread needs 14 risers of 7.714 inches and 13 treads. The total run is 130 inches, the stringer about 169 inches and the angle 37.6°, which meets the code limits.

Tips for best results

Check every box before you rely on a result, because one wrong digit changes the whole answer. Use the exact figures from your payslip, bill, certificate or contract, and keep a note of the date you calculated. Rates, thresholds and rules change from time to time, so for tax, fees and legal matters treat the output as an estimate and confirm with the official source named on this page. You can run as many scenarios as you like; nothing is saved or sent, and refreshing the page clears the boxes.