*The measurements in the chart are from on our own measurements here at iPenstore using a digital micrometer. We measured both the actual nib tip, and a sample writing line (an average down stroke on Rhodia 80g High Grade Vellum Paper), to get the most accurate measurement possible. For each nib size, we measured multiple nibs from each brand, then took the average size, rounded to the nearest tenth of a millimeter, and used that number for the chart. Each number is an average nib tip size, and based on our current inventory. The numbers are accurate, but please keep in mind that there are variations in tip size. Therefore, this chart is best used as reference point and comparison tool.