How to Make your Own File Folder Labels | Avery.com 2. Measure the file folder tab. Once you know how your filing system will be organized it's time for the next step: finding the right label size. Most file folder tabs will fit a standard 2/3″ x 3-7/16″ file folder label but it's always a good idea to grab a ruler and double check. Some file folders may be designed to fit a larger 15/16 ...