Dowel Spacing
Calculator
Results
- Usable length (mm)
- 500
- Centre-to-centre spacing (mm)
- 125
- First dowel centre from the end (mm)
- 50
- Last dowel centre from the end (mm)
- 550
Results
| Usable length (mm) | 500 |
| Centre-to-centre spacing (mm) | 125 |
| First dowel centre from the end (mm) | 50 |
| Last dowel centre from the end (mm) | 550 |
formula-map diagram
- Usable length (mm)
- 500
- Centre-to-centre spacing (mm)
- 125
- First dowel centre from the end (mm)
- 50
- Last dowel centre from the end (mm)
- 550
Formula map
Formula
Spacing = (length − 2 × margin) ÷ (dowels − 1)= 500
Note
This result is a simplified model; verify against your shop's own tolerances and material data before cutting.
More in Woodworking and metalwork
See all →Frequently asked questions
How does this calculator decide where to place dowels?+
Given the length of the joint edge and either a desired number of dowels or a maximum spacing, it distributes dowel positions evenly along the edge while keeping a minimum edge margin from each end, since a dowel placed too close to the end of a board risks splitting the wood.
Why shouldn't dowels be spaced too far apart?+
Wide dowel spacing leaves unsupported sections of the joint free to flex or gap open under load, weakening the glue line between dowels. A denser spacing spreads clamping pressure and stress more evenly across the whole joint.
Why shouldn't dowels be spaced too close together either?+
Dowels placed too close together reduce the amount of solid wood between holes, which can weaken the board and makes drilling accurately harder since the holes' glue-relief chambers can intersect. A practical minimum spacing is usually several times the dowel's diameter.
Does board thickness affect dowel placement?+
Yes, thickness determines dowel diameter and therefore minimum edge distance and spacing: a thin board can only safely fit a small-diameter dowel positioned well clear of both faces, which limits how many dowels of a workable size actually fit.
Why is precise dowel alignment more critical than with biscuits?+
Dowels rely on exact hole alignment between the two mating boards; even a small marking or drilling error causes visible misalignment at the joint face. This is why doweling jigs exist, and why this calculator's evenly spaced layout is meant to be transferred with a jig or story stick rather than measured freehand on each piece.