Dovetail Angle Calculator

Calculate dovetail joint angles, pin width, tail width, and slope ratio for woodworking and machining applications.

Material Type

Board Thickness (mm)

Tail Width at Widest Point (mm)

Pin Width at Narrowest Point (mm)

Slope Ratio 1:N (N value)

Results will appear here.

1. Dovetail angle from slope ratio:
θ = arctan(1 / N)
where N is the slope ratio denominator (e.g. 8 for 1:8).

2. Actual dovetail angle from dimensions:
rise = (Tail Width − Pin Width) / 2
θ_actual = arctan(rise / Board Thickness)

3. Actual slope ratio from dimensions:
N_actual = Board Thickness / rise

4. Saw angle from vertical:
Saw Angle = 90° − θ_actual

5. Taper per side (undercut depth):
Undercut = (Tail Width − Pin Width) / 2

Slope ratio 1:8 is standard for hardwoods; 1:6 for softwoods (Taunton Press, The Complete Illustrated Guide to Joinery).
Ratios below 1:5 risk short-grain breakage; above 1:12 the joint may slip under shear load.
The baseline (marking gauge setting) equals the mating board's thickness.
Calculations assume a symmetric single dovetail; for multiple tails, spacing is applied per tail unit.
All dimensions in millimetres; angles in degrees.
Formula reference: Rogowski, G. (2002). The Complete Illustrated Guide to Joinery. The Taunton Press.

In the network