The dowel joint calculator finds the right dowel diameter, spacing, and insertion depth for your wood joint. Correctly sized dowels prevent splitting, ensure alignment, and create joints that will last decades.
Dowel Joint Calculator
Thinnest board in the joint
Length of the mating edge
How to Make Accurate Dowel Joints
Dowel joints combine strength and alignment. This dowel joint calculator gives you the specs so your holes line up perfectly on both mating pieces.
Mark and Drill
Use a doweling jig or self-centering dowel jig for consistent hole placement. Drill perpendicular to the surface — angled holes cause the joint to skew when assembled. Drill 1/16\" deeper than calculated to account for glue squeeze-out. Use a brad-point bit for clean entry holes.
Glue and Assemble
Apply PVA glue to both holes and both ends of each dowel. Work quickly — you have 5–10 minutes before the glue becomes tacky. Assemble dry first to confirm alignment. Pre-fluted dowels allow excess glue to vent upward; smooth dowels can hydraulically lock and prevent full seating.
Frequently Asked Questions
Is this dowel joint calculator free?
Yes, completely free. All calculations run locally in your browser.
What size dowel should I use?
The dowel diameter should be no more than one-third the thickness of the thinnest board. For 3/4" (19mm) stock, use 1/4" or 5/16" dowels. For 1-1/2" (38mm) stock, 3/8" or 1/2" dowels work well. Using an oversized dowel can split the wood when the joint is assembled.
How deep should dowel holes be?
Each hole should be half the dowel length plus 1/16" for glue expansion. For a 2" dowel, drill 1-1/16" deep in each mating piece. Most commercially-available dowels are 1-1/2" to 2" long. Pre-fluted dowels allow excess glue to escape, preventing hydraulic pressure from splitting the joint.
How far apart should dowels be spaced?
Dowels should be spaced 2–4 inches apart for edge joints (face frame assembly, table top edge strips). For butt joints in cabinet carcasses, 3–6 inches. Don't use fewer than 2 dowels per joint — a single dowel can rotate. Always test alignment with a dry fit before gluing.
Are dowel joints strong?
Dowel joints are strong in shear and moderate in withdrawal. For cabinet face frames and shelf dadoes, they provide excellent alignment and adequate strength. For chair legs and structural joints under high stress, mortise-and-tenon joints are stronger. Dowel joints excel when combined with glue.