You will hear plenty of folks say it does not really matter; just get close and you will be fine. But if you have ever driven a screw and felt it spin in the hole instead of snug up, you know ‘approximate’ is not always good enough.
We are timber construction professionals with decades on the tools, and we’re sharing with you how to know what drill bit to use for wood screws to prevent wood splitting, cam-outs, screw snaps, and more!
TL;DR (Key Takeaways)
- The size of the hole for wood screws for pilot holes should be smaller than the minor diameter (the size without the threads) of the screw for softwoods. For hardwoods, use a larger bit for pilot holes.
- The size of the hole for wood screws for clearance holes should be the same size or slightly larger than the major diameter (the size with the threads) of the screw.
- You can know what drill bit to use by “eyeballing” it or using a caliper. For beginners (and people with bad eyesight), the easiest way is to buy a wood screw gauge on Amazon. Just slide your bit or your screw into the slot for the type of wood you’re using, and you’re done.
- Always use pilot holes for stainless steel wood screws.
- Always drill clearance holes when joining two pieces of hardwood.
What drill bit to use for wood screws?
The drill bit to use for wood screws depends on the wood you’re fastening, if you’re drilling a pilot hole or a clearance hole, and your screw’s diameter.
Before picking the right drill bit size, here’s a detailed explanation of all of them.
1. Understanding the Screw’s Features
You need to know your screw’s shank diameter, major diameter (overall diameter), and minor diameter (the central spine).
IMPORTANT: Not all screws are the same. There are brands whose wood screws have a shank that has the same size as the minor diameter, and there are some that are slightly bigger than the minor diameter.
2. What Type Of Hole You Need EXACTLY
When someone says “pre-drill holes,” they usually mean pilot holes, unless you are joining two wood pieces, in which case you would use clearance in the top piece, pilot in the bottom, and a countersink on top.
Pilot Holes
You need to use pilot holes for wood screws to keep the wood from splitting and to guide the screw so it runs straight.
The pilot holes must not be the same size as the screw. You're going to find online how-to guides that say, "Match the bit to the size of the screw," but that's completely false (like we've mentioned above, it's not always that a shank is the same size as the minor diameter).
Size the pilot to the screw’s minor diameter, not the major diameter. You want the threads to bite, so the bit must be smaller than the major diameter or the outer thread.
When to Use Pilot Holes:
-
Always
- Joining two pieces of softwood.
- Close to edges of solid wood, into end grain, or near board ends
- Tropical hardwoods
- Hardwood decking boards into joists.
- Using stainless steel wood screws, very long screws, or cheap black drywall screws
- Hinges and small hardware where precision matters
- Very old or dry wood
- Not usually
- Screwing away from edges
Clearance Holes
A clearance hole is a hole that's equal to or slightly bigger than the major diameter (the threads). The screw should slip through no problem and doesn't grab anything. A clearance hole in the top piece lets the threads bite in the bottom piece and pulls the two pieces of wood together into a cleaner, firmer joint.
When to Use Clearance Holes:
-
Always
- The top board is dense hardwood or laminate, and you want the shank to slide with no thread engagement in the top board.
- You are using fully threaded screws and need the top board to move freely so the screw can pull the parts together.
- You are pulling down cupped or warped boards and need strong pull-down pressure without the top board binding on the threads.
- Very long or stainless screws where friction in the top board makes driving difficult
- Fastening near the edge of the top board to lower split risk from thread bit.
- Not usually
- Joining two pieces of softwood
Pocket hole joinery where the pocket path already provides a slide hole for the shank
Countersink Holes
A countersink hole provides a space for the screw head to sit flush or slightly below the surface, helping to prevent splitting. Always drill your countersink holes first, before the pilot and clearance holes. If you countersink after drilling, the result can be wavy and uneven, whereas countersinking first ensures the hole’s outline is clean and uniform.
When to Use Countersink Holes:
-
Always
- Hardwood with wood screws, countersink first to cut down on splitting
- You don't want the screw heads to protrude.
- You want to conceal the screw and create a smooth finish by filling the countersink hole with a wood filler.
- Construction screws that “usually countersink themselves” still benefit from a light clean-up.
-
Not usually
- Pan, round, washer, or hex head screws designed to sit on the surface.
- Structural connectors or hardware that do not specify countersinking.
3. Drilling Pilot Holes on Softwood vs. Hardwood
Choosing the drill bit for pilot holes in wood depends on the kind of wood that you are fastening to.
For hard materials, the threads need to grip all the way into the root of the screw, while for softer materials, you want a bit of compression to help the threads bite into the wood without causing it to split.
Softwood: When you're driving screws into softer woods like pine, cedar, or spruce, the wood has more give, so you don’t need as much force. For these, you want to use a drill bit that’s slightly smaller than the minor diameter of your screw.
Hardwood: Hardwoods like oak, maple, walnut, or cherry are much denser and require more force to drive the screw. In these cases, you want the pilot hole to be equal to or slightly larger than the screw’s minor diameter. This gives the screw’s threads room to engage with the dense wood without causing the screw to snap or the wood to split.
When joining two pieces of softwood, all you really need is a pilot hole. When joining two pieces of hardwood, a simple pilot hole often isn’t enough by itself. That’s where a clearance hole in the top workpiece comes in.
You drill the clearance only through the top piece, so the shank slides through freely. That way the threads bite only in the lower piece, and the screw can pull the two parts together like a clamp.
Below are ways that you can use in picking the right drill bit size for pilot holes and clearance holes.
How to Know What Drill Bit to Use
When choosing the right drill bit for wood screws, there are many ways you can use it. Let’s go through a few quick ways to figure it out, whether you're eyeballing it, checking product specs, or using charts.
1. Eyeballing It
One simple way to choose the right drill bit is by eyeballing it. Take the drill bit you think is the right size and hold it in front of the screw. Then, close one eye and give it that "stink-eye" look.
For pilot holes, you should see threads on both sides of the screw. If you don’t see any threads, that means the drill bit is too big, so try a smaller size. If you see the threads, you've got the right drill bit!
For clearance holes, you should not see any threads. It’s not always super precise, but it’s an easy way to get the job done quickly.
2. Using a Pilot Hole Drill Guide (Gauge)
If your eyesight isn’t what it used to be and eyeballing it no longer works, a pilot hole drill guide (wood screw gauge) makes picking the right bit fast and foolproof.
A wood screw gauge typically has columns for screw size, softwood, and hardwood, with holes for tapered and straight bits.
- Slide your bit into the softwood or hardwood slot you’re using to see which screw size it pairs with (e.g., a 1/8" straight bit in the softwood column might point you to a #10 screw).
- Or do it in reverse: insert the screw into the guide, and it shows you the matching drill bit.
This tool removes guesswork fast and keeps your pilot sizing consistent across projects.
3. Using a Caliper
If you want something that's more precise, you can measure the screw’s diameters with a caliper.
For pilot holes, if your screw measures about 0.127 inches, choose a drill bit that’s just slightly smaller than that. A 1/4" or 1/8" drill bit usually works well.
For clearance holes, it should be equivalent to or slightly larger than the major diameter.
4. Finding a Chart Online
You can also use an online chart to know what drill bit to use, which is the easiest way to do it. Just look up "wood screw hole chart" on Google or Bing. There are many websites and forums that share the recommended drill bit sizes based on screw sizes or gauges.
However, not all online charts may give the same information. Below is an expert-approved wood screw hole chart.
5. Reading the Label on the Packaging or Box
A quick way to pick the right drill bit size is to check the information on the box or packaging of the screws. Most wood screw makers put the diameter of the screw on the box.
The diameter listed on the box refers to the major diameter of the screw, and this is what you'll use to guide your pilot hole size.
6. Visiting the Wood Screw Manufacturer's Website
If you want something more specific than what's said on the box, you can visit their website. Established wood screw manufacturers, like Eagle Claw and Simpson Strong-Tie, offer detailed technical data sheets. These data sheets include the minor, shank, and major diameters of their screws.
The manufacturer-provided data allows you to easily select the right drill bit size to use based on the screw's exact dimensions.
Stop Wood Splitting When Screwing! Choose the Right Drill Bit
At ATC Construction Fasteners, we’ve been in the timber trenches for years. We’ve seen the splits, snapped screws, and “Why won’t this pull tight?” moments. We know how to fix them fast. The real win isn’t luck. It’s choosing the right bit for the right screw every time.
Since 2008, we’ve stocked the gear that actually solves problems on site. Our Eagle Claw stainless wood screws (tens of millions sold) sit alongside Simpson Strong-Tie, so you get strength, corrosion resistance, and pro-grade reliability.
Got a project? Tell us the timber species, screw size, and where it’s going. We’ll help you match the bit, dial in your pilot/clearance/countersink sequence, and pick a fastener that lasts (from coastal decks to commercial frames).
FAQs
What setting do you use to drill screws in wood?
The setting to drill your screws should be low or medium to start. As a simple rule of thumb, the softer the material, the lower the torque you should use. The same goes for screw size. Set your drill or driver's clutch to lower torque when using small screws so you don’t overpower them.
If you use too much torque, you can overdrive the screw and bury it too deep in the workpiece, or you can strip the screw head, which makes it a pain to drive further or remove later.
What size drill bit for a #8 wood screw?
For #8 wood screws, use the 3/32-inch drill bit size for softwood and a 1/8-inch drill bit for hardwood when drilling pilot holes.
What size pre-drill for a #10 screw?
For #10 screws, you should pre-drill using the size 1/8" for hardwoods and 7/64" for softwoods.
