Webs that have crossweb variation in machine direction length are commonly called "Baggy Webs". All real webs have some degree of bagginess. When the bagginess exceeds some quantity, web handling problems such as wrinkling and lateral motion begin to appear.

There have been many articles, technical papers and patents on the subject of web bag measurement. This paper will summarize the measurement methods in the open literature. New mathematical techniques will be presented to quantify baggy webs. A new concept of "Web Bag Strain" will be presented for the quantification of baggy webs.