The purpose of this work was to develop tools for analysis of breakage in cotton during mechanical handling, such as ginning or lint cleaning. The scope was limited specifically to the number-weighted fiber properties. This was because these fiber properties have the special feature that simple, practical relationships exist between the average values, a situation that does not obtain for the mass-weighted means. In the first part of this work, important engineering research tools were developed for analysis of the degree and nature of breakage in a batch of cotton being processed through individual stages of machinery. That “saved-ends” analysis was based on the tracking of number-mean length under the assumption of negligible fiber waste. The purpose of the second half of this work was to adapt the mathematical tools to the more practical analysis of breakage in cases where wastes are generated, and the amount of fiber waste cannot be ignored.