The easiest way to determine the percent slope of an area is to measure the
change in height (elevation over a measured distance), then calculate the
percentage of slope. Use the following formula to determine slope:

Rise ÷ Run = Slope %

OR

(Change in elevation÷ measured distance = slope %)

e.g. 30 metres ¸ 100 metres = .3 or 30%

Calculating a slope steepness index for
a map area

Stages:

Calculate map area in km˛

Place 10 X 10 grid overlay over map

Calculate % slope for each grid square

Present results as an area average or median slope for the area
(see chart example below)