What size dowels should I use?

The dowel diameter should be no more than half the board thickness. For 18mm stock, use 8mm dowels. For 25mm stock, 10mm or 12mm dowels work well. For 12mm stock, use 6mm dowels.

How far apart should dowels be?

Space dowels 75–150mm apart for edge joints. For structural joints, closer spacing (75–100mm) is better. For panel alignment, 150mm is adequate since the glue provides most of the strength.

How deep should dowel holes be?

Each hole should be half the dowel length plus 1–2mm clearance for excess glue. If using 30mm dowels, drill each hole to 17mm deep. Never drill so deep that you risk breaking through.

Do I need dowels for edge joints?

Technically, a properly glued edge joint in solid wood is stronger than the wood itself. Dowels primarily help with alignment during glue-up rather than adding strength. Many woodworkers prefer biscuits or dominos for alignment.

WoodCalcs

Dowel Spacing Calculator — Edge Joint Dowels

Calculate optimal dowel positions and spacing for edge joints, face joints, and panel glue-ups.

Joint Length

Total length of the joint

Board Thickness

Dowel Diameter

How We Calculate This

This calculator determines dowel positions along a joint for proper spacing and edge distance.

Edge distance

Minimum distance from each end = 2 × dowel diameter (to prevent splitting).

Spacing

Dowels are spaced at approximately 100mm centres within the available length after edge distances.

Dowel length

Dowel length = minimum of (2 × board thickness) and (5 × dowel diameter), ensuring adequate penetration without risk of breakthrough.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.