Drill bit size for screws is very important for screw driving. Because wood edges can be cracked easily while screws are driving inside the wood, 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. But we use a range in woodworking. We mostly use #1 as the smallest size screw, which has a 1/16″ diameter. The largest is #24, with a 3/8″ diameter. For the #1 screw, we can use a 1/32″ drill bit for both softwood and hardwood. As well as for the largest screw; we can use 3/16″ for the softwood and 7/32″ for hardwood. Other drill bit sizes for screws are as below.
Importance of Drill Bit Sizes in Screw Driving
Normally, impact drivers are used to drive screws into wood efficiently. When the screw is driven into wood, the surface material is compressed. As a result of this, it will crack easily. This is common for softwood and wood edges. In order to prevent this problem, the predrilled hole is used to drive the screws.
A predrilled hole is always smaller than the screw. Hence you should know the available drill bit sizes for screws every time.
A pilot hole is named a predrilled hole in the material to stop drill bit slipperings and improve accuracy and starting angle drillings.
How to Choose the Right Drill Bit for Screws?
It is important to choose the right drill bit for screw pilot holes.
When you select a drill bit for screws, makesure it has a lower diameter than the major diameter of the screw and the length of the screw.
Do not choose a drill bit size similar to the major diameter of the screw. Then it will not tighten in the hole, and soon the screw will lose.
Drill Bit Sizes For Screws for Both Softwood and Hardwood
| Screw Number | Screw Size in Inches | Screw Size in mm | Drill Bit Size For Softwood | Drill bit size for Hardwood |
| #1 | 1/16 | 1.58 | 1/32 | 1/32 |
| #2 | 5/64 | 1.98 | 1/32 | 3/64 |
| #3 | 3/32 | 2.38 | 3/64 | 1/16 |
| #4 | 7/64 | 2.77 | 3/64 | 1/16 |
| #5 | 1/8 | 3.17 | 1/16 | 5/64 |
| #6 | 9/64 | 3.57 | 1/16 | 5/64 |
| #7 | 5/32 | 3.96 | 1/16 | 3/32 |
| #8 | 11/64 | 4.36 | 5/64 | 3/32 |
| #9 | 3/16 | 4.76 | 5/64 | 7/64 |
| #10 | 13/64 | 5.15 | 3/32 | 7/64 |
| #11 | 7/32 | 5.55 | 3/32 | 1/8 |
| #12 | 15/64 | 5.95 | 7/64 | 1/8 |
| #14 | 1/4 | 6.35 | 7/64 | 9/64 |
| #16 | 17/64 | 6.74 | 9/64 | 5/32 |
| #18 | 19/64 | 7.54 | 9/64 | 3/16 |
| #20 | 5/16 | 7.93 | 11/64 | 13/64 |
| #24 | 3/8 | 9.52 | 3/16 | 7/32 |
