What Size Drill Bit for #8 Screw?

By the end of this article, you’ll know what size drill bit you need for a metal eight screw.

Even though screws come in many sizes, the #8 screw is much more influential than the others. It is an ideal size for most woodworking projects. So, next time you plan to use the #8 screw, you should know the correct drill bit sizes. I can tell you from experience that knowing these things in advance will help you a lot in your woodworking projects.

In general, to drill a pilot hole for the #8 screw on softwood, you’ll need a 5/32-inch drill bit. For hardwood, use an 11/64-inch drill bit. However, the common drill bit size for the #8 screw is 1/8 inch.

What are the Factors that I Should Look Out For?

You should consider one major factor while choosing a correct-sized drill bit for the #8 screw. The drill bit hole size changes according to the type of wood.

If you are drilling softwood, you can choose a smaller drill bit. However, drilling hardwood is entirely different, and you’ll need a much larger drill bit. But remember, the 1/8-inch drill bit is the standard size for the #8 screw.

Difference Between Softwood and Hardwood

If you ever had the chance to drill two wood pieces made from softwood and hardwood, you probably know how hard it is to drill the hardwood compared to softwood. But if you haven’t had such an experience, don’t worry. I’ll shed some light on the subject.

Generally, hardwood is much more durable than softwood. Hence, if you use a drill bit to create a 0.25-inch pilot hole on a piece of softwood, you cannot get the same results on a piece of hardwood with the same drill bit. In other words, to make a 0.25-inch pilot hole on hardwood, you’ll need a much larger drill bit. So, the same theory applies when drilling a pilot hole for the #8 screw.

What Size Drill Bit for 8 Screw Metal

As mentioned above, a 1/8-inch drill bit is the standard size for the #8 screw. However, if drilling into hardwood, use the 11/64-inch drill bit. For softwood, use the 5/32-inch drill bit.

Quick Tip: The diameter of the #8 screw is 0.15625 inches.

Follow the below table for thread diameters for various screws.

Thread Diameter
Screw SizeNearest FractionInchMillimeter
#01/160.061.5
#15/640.071.8
#23/320.082.0
#37/640.092.3
#47/640.112.8
#51/80.123.1
#69/640.133.3
#85/320.164.2
#103/160.194.8
#127/320.215.5
#141/40.246.3

Why Should I Pre-Drill the Pilot Hole?

This is a predicament that most people get into while working on a woodworking project. Should I pre-drill the pilot hole? Or should I use the screw’s sharp end? (1)

Well, depending on your situation, both solutions can be accomplished. For instance, if drilling with small drill bits, there is no need to create a pilot hole. Instead, use the sharp end of the screw to navigate through the wood without much issue. (2)

However, when you use large drill bits, things could go haywire quickly. I meant you’ll have a hard time navigating the drill bit. So, creating a pilot hole is the safest and easiest technique for this kind of situation. A small pilot hole can change the course of your task.

Quick Tip: Regardless of the drill bit sizes, I strongly suggest you create a pilot hole before starting the drilling process.

Take a look at some of our related articles below.




References
(1) woodworking project – https://www.popularmechanics.com/home/how-to-plans/how-to/g2835/woodworking-projects/
(2) wood – https://www.britannica.com/science/wood-plant-tissue

Video References

Bob’s Wood Stuff

Training Hands Academy

Steve Ramsey – Woodworking for Mere Mortals

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.