Pocket screw length chart

Which Kreg pocket screw goes with which board thickness. Kreg makes the system, so its own chart is the authority: the table below is that chart, from the Kreg Jig K4 owner's manual, with the jig and drill-collar setting that goes with each thickness.

Screw length is measured from under the head to the tip. At 1/2 in: Kreg recommends a pan-head screw at this thickness; with its Micro-Pocket drill guide, a 3/4 in screw. The millimetres are the manual's own, rounded to the whole millimetre.

Fine or coarse thread

Kreg's manual gives one rule: fine-thread screws (#7) in hardwoods, because the smaller diameter and pitch are less likely to split them, and coarse-thread screws (#8) in softwoods and composites, where the larger thread holds better.

Fine thread, #7

Ash, Oak, Maple, Walnut, Hickory, Cherry, Mahogany, Birch

Coarse thread, #8

Pine, Cedar, Basswood, Poplar, Plywood, MDF, Particleboard

Joining two thicknesses

Kreg's advice is to drill the pocket in the thinner piece and set the jig and the bit for that thickness. When the outside faces are flush, pick the screw for the thinner piece too. Kreg says a longer screw can add strength when the joint is offset, but gives no length for it, so neither do we. More on the joint itself: pocket hole joinery.