Screw size charts are available at the websites of W. L. Fuller, Inc., Engineers Edge and Jamestown Distributors. All of these websites also offer additional information about choosing the right screws for a particular project.
The screw chart available at the first site features standard wood screws sizes and includes head bore size, screw shank, straight pilot drill size, tapered pilot drill size and the recommended countersink number. On Engineers Edge's page, users can find a chart that illustrates screw size, class thread, major diameter, pitch diameter and minor diameter. The screw size chart available from Jamestown Distributors includes the maximum head diameter, basic decimal size, nearest fractional equivalent and threads per inch for each of the screw numbers listed.