Pocket Hole Screw Length Chart by Thickness

A pocket hole screw that runs a quarter inch too long comes out through the face of the board you were trying to hide the joint in. One that runs short catches a few threads and lets go the first time the joint takes weight. Length is not a matter of preference here. It is set by the thickness of the board you drilled the pocket into, and the company that invented the jig publishes an exact number for every thickness. This page is that chart, the two places where the right answer is not obvious, and an honest note about where the other charts on this topic disagree with the manufacturer.

For three quarter inch stock, the thickness most furniture and cabinet parts are milled to, use a 1-1/4 inch pocket hole screw. Kreg's published chart runs from half inch material at a 3/4 inch screw up to 1-1/2 inch material at a 2-1/2 inch screw. Set the drill guide and the depth collar to that same thickness, then pick coarse thread for softwood and sheet goods or fine thread for hardwood.

• Measure the actual thickness, not the nominal size. A 2x4 is 1-1/2 inches thick, not 2 by 4.
• Three quarter inch stock takes a 1-1/4 inch screw. That single row covers most projects.
• Half inch stock is the exception and has two correct answers depending on which drill guide you own.
• Coarse thread for pine, cedar, poplar, plywood and MDF. Fine thread for oak, maple, cherry and walnut.
• Joining two thicknesses: drill the pocket in the thinner board and size everything to that board.
• The drill guide setting, the depth collar setting and the screw length are all the same number.
• Popular charts for this query disagree with the manufacturer on 5/8, 3/4 and 1 inch stock. The chart below is the manufacturer's.

The Pocket Hole Screw Length Chart

In short: find your actual material thickness in the left column and read across.

These are the lengths published by Kreg, the company whose jig defined the format. The drill guide setting and the depth collar setting are the same number as the material thickness, so once you have measured the board you have set all three.

Source: Kreg's screw selection guide and published chart.

Measure the Board, Not the Label

In short: nominal lumber sizes are bigger than the board in your hand, and the chart wants the board.

Softwood sold at a home center carries a nominal name rather than a measurement. A 2x4 finishes at 1-1/2 inches by 3-1/2 inches. A 1x6 finishes at 3/4 by 5-1/2. Hardwood sold in quarters is worse, because 5/4 stock leaves the mill at 1-1/4 inches and can arrive anywhere from 1 inch to 1-1/8 after surfacing, which is why the chart has rows for both.

Put calipers or a rule on the actual board before you set the jig. Every downstream setting depends on that one number, and a board you assumed was 3/4 that turns out to be 13/16 will change nothing, while a board you assumed was 3/4 that turns out to be 5/8 will put a screw tip through the face.

Half Inch Stock Has Two Right Answers

In short: 3/4 inch pan head with a Micro-Pocket guide, 1 inch pan head with a standard guide.

This is the row that gets flattened into a single number on most charts, and it is the one where being wrong shows on the outside of the work. Half inch material is thin enough that the pocket itself takes up most of the board, so the screw length depends on which drill guide cut the pocket.

• Standard drill guide in half inch material: 1 inch pan head screw.
• Micro-Pocket drill guide in half inch material: 3/4 inch pan head screw.

Pan head rather than washer head, for all half inch material. The washer head is wider and sits in a pocket that half inch stock does not have the depth to hold cleanly.

Coarse Thread or Fine Thread

In short: coarse bites soft fibers, fine avoids splitting dense ones.

Thread choice is about density, not about hardwood versus softwood as trade names. Coarse threads are deep and aggressive, which is what soft, open fiber needs in order to hold. Run those same threads into oak or hard maple and they displace more fiber than the wood will give up, and the board splits along the pocket.

Coarse thread: pine, cedar, fir, spruce, poplar, aspen, basswood, and the sheet goods, meaning plywood, particle board, MDF and melamine.

Fine thread: oak, maple, cherry, birch, ash, walnut, mahogany, hickory.

Plywood goes with the coarse group even when the face veneer is a hardwood, because the core is what the threads are holding. If you are unsure where a species sits, the types of wood guide covers the density differences that drive this choice.

Where the Popular Charts Disagree With the Manufacturer

In short: three of the most visible charts publish different numbers for the most common stock.

We read the pages currently ranking for this term before writing, and they do not agree with each other. On 3/4 inch stock, the row nearly everyone needs, one chart says a 1-1/4 inch screw and another says 1-1/2. On 5/8 inch stock one says 1 inch and another says 1-1/4. On 1 inch stock the answers are 1-1/2 and 2. Those are not rounding differences. A 1-1/2 inch screw in 3/4 inch stock has a quarter inch of extra length to put somewhere.

Some of the disagreement comes from a formula that circulates with these charts: screw length equals material thickness plus 5/8. It is a tidy rule and it does not reproduce the manufacturer's chart. Three quarters plus five eighths is 1-3/8, and the chart says 1-1/4. Half plus five eighths is 1-1/8, and the chart says 3/4 or 1. The formula was reverse engineered from a couple of rows and then applied to all of them.

Use the published chart. It is not derived from a rule, it is the set of lengths the screws are made in, matched to the pocket geometry the jig drills.

Joining Two Boards of Different Thickness

In short: pocket the thinner board and size everything to the thinner board.

A 3/4 inch rail meeting a 1-1/2 inch leg is the common case. Drill the pocket in the 3/4 inch rail, set the guide and collar to 3/4, and use the 1-1/4 inch screw. The screw is sized so that it clears the pocketed board and lands roughly half an inch into the second one, and that half inch of engagement is where the strength is. Sizing to the thick board instead sends the tip somewhere you did not plan.

The joint still needs the mating faces flat and clamped while the screw draws them together, which is the same requirement as any other mechanical joint. Our guide to achieving perfect joints covers the clamping side, and joint techniques covers when a pocket screw is the wrong choice and a mortise or a dovetail is the right one.

Spacing, Splitting and the Mistakes That Cost a Board

In short: two holes on narrow parts, six to eight inches apart on wide ones, and stop at snug.

A single pocket screw is a pivot. Narrow parts such as face frame rails want two holes side by side so the piece cannot rotate as the screw draws it home. Across a wide panel, space the holes six to eight inches apart.

Splitting near the end of a board is usually thread choice rather than screw length. Fine thread in hardwood, and keep the pocket back from the extreme end of the board. Overdriving is the other common cause: a pocket screw is done when the joint is tight, and another half turn past that strips the pocket in plywood and MDF, where there is no long grain to hold.

Glue is optional in a pocket screw joint and it does not hurt. On end grain it contributes little, which is worth knowing before you rely on it. Our guide to wood glues covers which adhesive suits which joint, and if you are working in a small space, essential tools for small shops covers the drill and clamp side of getting this done without a bench full of machines.

Pocket Hole Screw FAQ

What size pocket hole screw for 3/4 inch wood?

A 1-1/4 inch screw, with the drill guide and depth collar both set to 3/4 inch. Coarse thread for plywood and softwood, fine thread for hardwood.

What size pocket hole screw for a 2x4?

A 2-1/2 inch screw. A 2x4 is nominally two by four and measures 1-1/2 inches thick, and the chart is built on the measurement.

Can I use regular wood screws in a pocket hole?

No. A pocket hole screw has a flat bottomed head that seats squarely on the flat shoulder the jig drills. A tapered countersunk head wedges into that shoulder and splits the pocket, and a self tapping tip is what lets the screw start in a hole that was never pre drilled for it.

What happens if the pocket hole screw is too long?

The tip comes through the face of the mating piece, which on a cabinet side or a table top is the surface you were hiding the joint behind. Too short is quieter and worse in the long run, because the joint holds on a few threads and loosens under load.

Is the screw length different for plywood?

The length follows the thickness exactly as it does for solid wood, so 3/4 inch plywood takes the 1-1/4 inch screw. What changes is the thread: plywood takes coarse thread even when the face veneer is oak or birch, because the threads are holding the core.

Coarse or fine thread for poplar?

Coarse. Poplar is sold alongside hardwoods and priced with them, but it is soft and open enough that fine threads have little to bite.

Do the drill guide and the depth collar use different numbers?

No, and this is worth checking on your jig before a batch of parts. The guide setting, the collar setting and the material thickness are the same figure. The screw length is the one number that differs, and it comes off the chart.

Does a pocket hole joint need glue?

It works without. Glue adds long grain strength where the faces meet and adds little on end grain, so treat it as a bonus on rails meeting legs rather than as the thing holding the joint together.