Work out slope percent to degrees instantly with clear inputs, formula shown and shareable results.
Percentage slope is rise divided by horizontal run times 100, and the angle is its arctangent. 15% is 8.53 degrees, or 1 in 6.67. The two scales diverge sharply on steep ground: 100% is only 45 degrees, and a vertical face is infinite percentage - which is why highway signs use percentage and climbers use degrees.
Percent to degrees
angle = arctan(percent / 100)
Degrees to percent
percent = tan(angle) x 100
No, it is 45 degrees - equal rise and run. Vertical would be infinite percentage, which is why the scale is unhelpful for cliffs.
Highway grades rarely exceed 7%. Anything over 12% is exceptionally steep for a public road and over 20% needs specialist vehicles.