Refer to Machinery's Handbook 3rd Edition page 1618.
| Screw Size | Max. Screw Head OD (in) | Screw Body OD (in) | Screw TPI | Hard Wood | Soft Wood | Countersink Size | ||
| Tapered Bit | Straight Bit | Tapered Bit | Straight Bit | |||||
| #2 | 0.172 | 0.086 | 26 | 3/32" | 1/16" | 5/64" | 1/16" | 1/4" |
| #3 | 0.199 | 0.099 | 24 | 7/64" | 5/64" | 3/32" | 1/16" | 1/4" |
| #4 | 0.225 | 0.112 | 22 | 7/64" | 5/64" | 3/32" | 1/16" | 1/4" |
| #5 | 0.252 | 0.125 | 20 | 1/8" | 3/32" | 7/64" | 5/64" | 5/16" |
| #6 | 0.279 | 0.138 | 18 | 9/64" | 7/64" | 1/8" | 3/32" | 5/16" |
| #7 | 0.305 | 0.151 | 16 | 5/32" | 7/64" | 9/64" | 3/32" | 5/16" |
| #8 | 0.332 | 0.164 | 15 | 11/64" | 1/8" | 5/32" | 7/64" | 3/8" |
| #9 | 0.358 | 0.177 | 14 | 3/16" | 9/64" | 11/64" | 1/8" | 3/8" |
| #10 | 0.385 | 0.190 | 13 | 13/64" | 9/64" | 3/16" | 1/8" | 7/16" |
| #12 | 0.438 | 0.216 | 11 | 7/32" | 5/32" | 13/64" | 9/64" | 7/16" |
| #14 | 0.491 | 0.242 | 10 | 1/4" | 11/64" | 15/64" | 5/32" | 1/2" |
| #16 | 0.544 | 0.268 | 9 | 9/32" | 3/16" | 17/64" | 11/64" | 9/16" |
| #18 | 0.597 | 0.294 | 8 | 5/16" | 7/32" | 19/64" | 13/64" | 5/8" |
| #20 | 0.65 | 0.320 | 8 | 21/64" | 15/64" | 5/16" | 7/32" | 3/4" |
| #24 | 0.756 | 0.372 | 7 | 3/8" | 17/64" | 3/8" | 1/4" | 3/4” |