This chart has the information you need to plan the size of your wall.
For example, you are building a 45-degree wall. You are hoping for 16 feet long and don't want to go more than 10 feet tall. It's outside, so you can go as high as you feel safe. Keep in mind that safety is determined by how thick the padded surface is you are installing. Padding should be 1" of pad per one foot of wall height. So a 10-foot wall should have a 10" thick pad.
How to Determine Climbing Wall Length
1. Find the angle of the wall you want. If you want a 45-degree wall, look at the chart below and find the factor 16.97".
2. Multiply the 16.97" x 10' feet height of the wall you want = 169.7"= 14.14 feet. Make sure to know that a 45-degree wall standing 10 feet tall at the peak will be 14.14' feet long of 45-degree terrain.
Now comes the trick of the kickplate. The kickplate is important on steep so that you have room to cut loose with your feet low on the wall. The kickplate can be as small as 12" tall. You can go as high as you want however keep safety in mind. The higher the kickplate, the higher the peak of the wall will be. So if we add a 12" kickplate, our wall will now be 11' feet tall.