Section XI and Appendix D of Section VIII, Div. 3 of the ASME Code include an influence coefficients method for calculating Mode I crack tip stress intensity factors, K1. When outlining the technical basis for this method, Cippola mentions that the fiee surface correction factors G0, G1, G2 and G3, that are tabulated for uniform, linear, quadratic and cubic stress variations, respectively, were derived using Shen and Glinka’s weight functions for surface cracks in plates. In the interim, the authors and colleagues have extended the validity range of their weight functions for cracks in plates and developed solutions for internal or external cracks in thin- or thick-walled vessels. This paper is a comprehensive comparison of correction factors, Gi, obtained from weight functions for an edge or surface semi-elliptic crack in a plate with those obtained for a radial-longitudinal edge or surface semi-elliptic crack in a cylinder. The differences, which in some cases are large, and the well know uncertainties when calculating K1 for the surface points of cracks are discussed.