The Five Cut Method is a formula that helps you calculate the error per inch of your crosscut sled. It uses one piece of wood to compound the error of your sled - and help you get that error down to a tiny fraction of an inch. If you would like a deep-dive on the Five Cut Method and how to make an ultra-square crosscut sled, here's a recent blog we published that walks you step-by-step on how to construct it.
Following the instructions in the Ultra-Square Medium Sized Crosscut Sled video, make a cut on each side of a rectangular piece of wood on your crosscut sled, keeping the wood on the right side of the saw blade. Turn the wood 90 degrees counter-clockwise between cuts. After the 4th cut, turn 90 degrees again and cut a narrow strip (around 1/2") off the side of the wood. Measure the far (A) side, the near (B) side, and the length of the offcut.