# How To Figure And Calculate Stair Stringer Lengths

It isn't as difficult as you would imagine and with a little math and a few measurements, you can figure and calculate your own stair stringer lengths. In the picture above I placed an imaginary stair stringer in the exact location of the stairway, we're going to use as our example. However, it will be removed in a few of the pictures below, to provide you with a better understanding of the calculation process. The first measurement you need will be the horizontal length of the stairway. I removed the stair stringer from the picture above, because this is more or less what you would be working with. In the next step you will need to measure the vertical height of the stairway. I removed the stair stringer from the picture above, because this is more or less what you would be working with. In order to figure out the length of the stair stringer, all you need to do is use this math formula.

A squared plus B squared equals C squared.

(A times A) plus (B times B) = C - then all you need to do is find the square root of the total. For Example:

If distance A is 50 inches and distance B is 35 inches, then all we need to do is multiply 50 times 50 and then add the total to 35 times 35.

50 x 50 = 2,500
+
35 x 35 = 1,225

2,500 + 1,225 =3,725

Then place the number 3,725 into a calculator with a square root key and push the key, to receive your stair stringer length and measurement.

I came up with 61.03

This means the distance for C would be 61 inches and if we divide that number by 12 (feet), it would give us 5 feet and 1 inch. This is what the square root symbol looks like on a calculator.

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