Drill bit size for # screw is very important for screw driving. It denotes the drill bit size related to the screw number (#). It helps to choose the right drill bit related to a specific screw number. Because wood edges can be cracked easily while screws are driving inside the wood due to compressions in the wood piece. This is common for both softwood and hardwood. Normally, screws have a major diameter. When we choose a drill bit size for the screws, its size should always be less than the major diameter of the screw.
Screws are available in different sizes. The most used #6 screw drill bit size is 1/16, #8 screw drill bit size is 5/64, #12 screw drill bit size is 7/64. The drill bit sizes can be varied with the wood types: softwood and hardwood. The softwood is less strong and compressible than hardwood. Hence drill bit size for # screws is always less than the hardwood.
Drill Bit Size for # Screws: Softwood
Softwood is weak and less dense. Hence, softwood can crack easily. When a screw is driven into the soft wood, the inside of the driving hole can be compressed. As well as it will crack easily due to the weak fibers. This mostly happens at the edges of the wood pieces. When you use the drill bit sizes below, you can avoid it.
| Screw Number | Screw Size in Inches | Drill Bit Size For Softwood |
| #1 | 1/16 | 1/32 |
| #2 | 5/64 | 1/32 |
| #3 | 3/32 | 3/64 |
| #4 | 7/64 | 3/64 |
| #5 | 1/8 | 1/16 |
| #6 | 9/64 | 1/16 |
| #7 | 5/32 | 1/16 |
| #8 | 11/64 | 5/64 |
| #9 | 3/16 | 5/64 |
| #10 | 13/64 | 3/32 |
| #11 | 7/32 | 3/32 |
| #12 | 15/64 | 7/64 |
| #14 | 1/4 | 7/64 |
| #16 | 17/64 | 9/64 |
| #18 | 19/64 | 9/64 |
| #20 | 5/16 | 11/64 |
| #24 | 3/8 | 3/16 |
Drill Bit Size for # Screws: Hardwood
Hardwood is heavy, strong, and highly dense. When hardwood is drilling, its pilot hole should be larger than the softwood pilot hole. You can use the below drill bits sizes for hardwood screws.
| Screw Number | Screw Size in Inches | Drill bit size for Hardwood |
| #1 | 1/16 | 1/32 |
| #2 | 5/64 | 3/64 |
| #3 | 3/32 | 1/16 |
| #4 | 7/64 | 1/16 |
| #5 | 1/8 | 5/64 |
| #6 | 9/64 | 5/64 |
| #7 | 5/32 | 3/32 |
| #8 | 11/64 | 3/32 |
| #9 | 3/16 | 7/64 |
| #10 | 13/64 | 7/64 |
| #11 | 7/32 | 1/8 |
| #12 | 15/64 | 1/8 |
| #14 | 1/4 | 9/64 |
| #16 | 17/64 | 5/32 |
| #18 | 19/64 | 3/16 |
| #20 | 5/16 | 13/64 |
| #24 | 3/8 | 7/32 |
Can I Drive a Screw Without Predrilling Hole?
You can drive a screw without a pre-drilling hole in the wood. You should not drive screws in the wood edges or close to the hole or void area. Because wood can be cracked easily at close ot edge, or hole. In order to prevent this you should drill a pilot hole in the workpiece using a suitable drill bit size.
