Dovetail angle chart
A dovetail's slope is written as a ratio, 1:r, meaning the side moves 1 unit across for every r units along. The angle from square is the arctangent of 1/r, so 1:6 is about 9.5° and 1:8 about 7.1°. The tables below give both directions.
Ratio to degrees
| Ratio | Angle from square | Traditionally for |
|---|---|---|
| 1:4 | 14.04° | — |
| 1:5 | 11.31° | — |
| 1:6 | 9.46° | softwood |
| 1:7 | 8.13° | — |
| 1:8 | 7.13° | hardwood |
| 1:9 | 6.34° | — |
| 1:10 | 5.71° | — |
Traditional rule, stated by Fine Woodworking (Taunton Press), Lee Valley Tools and Rockler
Dovetails are traditionally cut at 1:6 in softwood and 1:8 in hardwood. That pairing is a shop tradition rather than a measured result, so it is labelled as a traditional rule and names the references that state it. The angles themselves are plain trigonometry.
Router bit angle to ratio
Dovetail router bits are sold by their angle. Turning an angle back into a ratio is 1 divided by its tangent. These are a few common bit angles; your jig's manual says which bit it was designed around.
| Bit angle | Ratio, about |
|---|---|
| 7° | 1:8.1 |
| 7.5° | 1:7.6 |
| 8° | 1:7.1 |
| 9° | 1:6.3 |
| 10° | 1:5.7 |
| 14° | 1:4 |
Lay out a joint
The dovetail calculator takes any ratio or angle and works out the tail and pin widths on both faces of your board, with the marks to scribe from the edge.
Sources
- Fine Woodworking (Taunton Press), Chris Gochnour, "Laying Out Dovetails", Fine Woodworking #190 (2007), read 2026-11-07
- Lee Valley Tools, Veritas Dovetail Markers (1:6 softwood, 1:8 hardwood), product 73357, read 2026-11-07
- Rockler, Rockler Dovetail Saddle Squares (1:6 and 1:8), read 2026-11-07