Change the Rise:Run or the angle to calculate the other.

 1: = Rise:Run Degrees

What angles do 1:6, 1:7, 1:8 correspond to?

Dovetails angles are often specified as a Rise:Run ratio, for example 1:7. This corresponds to the angle of a line that covers a vertical distance of 7 cm (or inches, or whatever unit you prefer) and deflects horizontally by 1 cm (or inches, or whatever unit you prefer).

Here are the angles that these rise:run ratios correspond to:

Rise:RunAngle
1:145.00
1:226.57
1:318.43
1:414.04
1:511.31
1:69.46
1:78.13
1:87.13
1:96.34
1:105.71
1:115.19
1:124.76

In case you are wondering, the formula to calculate the angle from a rise:run ratio is this:

``````arctan(rise/run)
``````

If you want to do this in a spreadsheet, use this:

``````=DEGREES(ATAN(rise/run))
``````

And here’s the opposite table from a few suitable angles to the corresponding rise:run, if you were wondering:

Angle (degrees)Rise:Run
51:11.43
61:9.51
71:8.14
81:7.12
91:6.31
101:5.67
111:5.14
121:4.70
131:4.33
141:4.01
151:3.73
161:3.49
171:3.27
181:3.08
191:2.90
201:2.75

The formula to go from an angle to Rise:Run is this:

``````Rise = 1
Run = 1/tan(angle)
``````

In case you are wondering what “the correct” angle is - there is no consensus whatsoever. Answers vary greatly depending on who you ask, but everything I have ever seen is between 1:4 (about 14 degrees) and 1:8 (about 7 degrees).