Formula to convert degree of slope to percent of slope.

I do not know what you mean by PI. Do you mean π, or do you mean some tool or add-in? Is this an Excel question?

The percent slope is the tangent of the angle (y/x, also called rise/run). So if you have the angle in degrees in A1, the percent slope would be

=TAN(RADIANS(A1))

Values as displayed

	A	B
1	Angle	Tangent (Slope %)
2	45	100.0%
3	10	17.6%
4	20	36.4%
5	30	57.7%

Underlying formulas

	A	B
1	Angle	Tangent (Slope %)
2	45	=TAN(RADIANS(A2))
3	10	=TAN(RADIANS(A3))
4	20	=TAN(RADIANS(A4))
5	30	=TAN(RADIANS(A5))