Mount Evans Road -- 13,300'

Difficulty Ratings (d=) Explained


You may have noticed that most of my hiking galleries have two numbers in parenthesis alongside their names. The first number is the TOTAL MILEAGE of the route (i.e. round-trip). The second number (d=) denotes a DIFFICULTY RATING. Developed by NOLS founder Paul Petzoldt, whom I've named the rating after, this particular rating system is the best I’ve yet found for standardizing the difficulty of hikes. It works as follows:


Petzoldt used 'energy units'  based on the length of the hike as well as the vertical gain along the route. One ‘energy unit’ is given for very mile travelled. Additionally, another ‘energy unit’  is given for every 500-feet of elevation gain.


For example, a one mile hike (1 energy unit) with 1,000-feet of gain (2 energy units) would give you a Petzoldt difficulty rating of d=3.00.  Consequently, a two mile hike (2 energy units) with only 500-feet of gain (1 energy unit) will also give you a rating of d=3.00.


Please note, however, Petzoldt ratings do not take into account weather, roughness of terrain, fitness level, trail conditions, etc. It is a rating system which simply gives a baseline difficulty for a particular hike under ideal settings.   A hike with an 'EASY' rating can become exponentially harder if you dump a couple feet of snow on the trail!


I've divided my hikes up into SIX levels of difficulty, based on the following Petzoldt difficulty ranges:


0.00-2.49 = EASY


2.50-4.99 = MODERATE


5.00-7.49 = CHALLENGING


7.50-9.99 = HARD


10.00-12.49 = VERY HARD


12.50 & up = EXTREME