Step 3 · Calculate the Average Width for a Custom Fit

Now for some simple math that makes all the difference. For each winder step, add the narrow edge measurement to the wide edge measurement, then divide that sum by 2. This result is the 'average width,' the number we'll use to create a beautifully proportioned, custom-made tread. It's also a good idea to note the smallest width you measured on each step; this serves as a helpful reference.