Slope can be defined in two units, DEGREE and PERCENT. It seems to be easy in converting each other. However, we often misunderstood and misnamed between the two. The most common mistake is, probably, giving 100% for 90o slope. Actually 90o slope is equal to a very large number (infinite) percent.
DEGREE has been widely known as slope unit and therefore people rarely do mistake in this unit. If the land is flat it is 0 (zero) degree, half between flat and step it is 45 degree, and a completely standing hill is 90 degree. Have a look at the following image as an illustration.
PERCENT is often mistakenly used. How many percent 0o, 45o, dan 90o above? The definition for PERCENT unit in slope is the tangen of the slope itself. For example, 45o can be calculated as follow
45o slope = slope of tan(45) in percent
Or if we want to get a number in percent directly we may put 100 in the formula as follow.
45o slope = 100 x tan(45) percent slope
The picture above shows that 45 degree slope is equal to 100 percent. Using tangen formula, we can calculate some conversion between percent and degree in slope as follow.
The tabel above shows that percent unit in slope ranges from 0 (zero) to infinite number. It is a mistake if we say that maximum percent number in slope is 100%, because slope of 100% actually for 45 degree. Hope that DEGREE and PERCENT units in slope can be used wisely.
