Calculate Stair Stringer Length

Figure and calculate stair stringer for length of wood to buy. You can simply figure about 14 inches per step and be close enough.

A multiplied times A + B multiplied times B = C multiplied times C.

Example: The stair riser A is 7 inches and the stair tread is 10 inches.

7 x 7 = 49 + 10 x 10 = 100 Next Step 49 + 100 = 149 Next Step You will need to find the square root of 149.

Next Step Enter 149 into the calculator and press the square root symbol and the answer should be 12.20655

C would equal 12 and 1/4 inches. Now just multiply 12.2 times the number of steps or treads to get the length of the stair stringer.