The calculation
The jig model is part of the answer
Material thickness controls the pocket location and drilling setup. It also affects the screw length, but the relationship depends on the jig and joint. This page deliberately identifies the K4 source. A different jig, micro-pocket accessory, thin plywood, or unequal-thickness joint may require another setup.
For the K4 chart’s 3/4 in row, the listed screw length is 1 1/4 in and the jig mark is 3/4 in. This is a lookup from the stated manual, not a rule obtained by multiplying thickness by a universal factor.
Measure actual material
A nominal board label is not an actual measurement. Measure the stock and consult the manual’s method for setting the jig and drill stop. This selector uses published rows only; it does not round an arbitrary thickness to a nearby row or decide how to join dissimilar thicknesses.
If your material does not match a listed setup, use the manufacturer’s current guidance for the exact model. Check screw-tip clearance on matching scrap before assembling a finished part.
Thread type and screw head still matter
The cited K4 manual distinguishes fine-thread screws for hardwood from coarse-thread screws for softwood and composite materials. Length alone does not select the complete product. Use pocket-hole screws and the specified head geometry, coating and thread for your jig, material and exposure.
Measure pocket screw length according to the maker’s convention. Do not substitute a conventional countersunk wood screw solely because its package lists the same length.
Questions from the workbench
Is this a chart for every Kreg jig?
No. It identifies the K4 manual as its scope. Other models and accessories can use different instructions, especially for thin material.
Can I use it when the two boards have different thicknesses?
This lookup is limited to equal-thickness stock. Use the manufacturer’s guidance for the specific unequal-thickness joint.
Sources and reference scope
Reference data checked November 7, 2026. K4 owner’s manual, matching material thickness. Metric equivalents on this page are calculated rather than copied rounded labels.
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