This paper presents a comparative assessment of three different approaches to highlight the importance of incorporating bottom and flank cutting edges in cutting force models for flat-end milling operation. The study focuses on identifying the most appropriate method that includes the effect of both cutting edges and predicts accurately over a wide range of cutting widths, i.e., axial depth of cut (ADOC) and radial depth of cut (RDOC). The first approach uses the average cutting constants directly estimated from the experimental force data. The second approach pre-processes the experimental data to exclude the contribution of bottom edges and determine flank constants for the estimation of cutting forces. The third approach considers the systematic derivation of independent coefficients for flank and bottom cutting edges and summing the individual contribution to determine cutting force. These approaches are implemented in the form of computational models, and machining experiments are conducted to examine the efficacy of proposed methods in estimating cutting force for flat-end milling operation. Based on the outcomes of the study, it is realized that the third approach can predict cutting forces accurately over a wide range of cutting widths. Also, it is observed that the bottom edge has a marked effect on the normal force component for select combinations of cutting widths. © 2020, Springer-Verlag London Ltd., part of Springer Nature.