Elevation gain and loss can seem very straightforward. But a lot of consideration went into giving you the most accurate idea of how much ascent and descent you would make on each hike in this hiking guide.
One of the things you'll notice in the hiking guide is that at the start of every hike and in the appendix at the back of the book I list the elevation gain of each hike. This is the amount of climbing you'll make during the length of a hike. Most guidebooks simply subtract the starting elevation from the destination elevation to determine the amount of elevation gain to expect. In theory this works but most hikes are more complex than this approach takes into account.
Many hikes have up and downs before you reach your destination and some hikes in Rocky Mountain National Park reach their highest point before you arrive at your destination. In the above graph we see the elevation profile graph for the hike to Mirror Lake. You'll notice that you begin the hike by descending down to the lowest point before you really begin the climb. Then, even on your way up you have a number of ups and downs before you eventually reach Mirror Lake.
In this hiking guide I've taken these ups and downs into account when calculating the total elevation gain. After studying many different hikes, I realized that I had to find the right balance. If I counted every little up and down it added a crazy amount of elevation gain to each hike, most of which would not even be noticed by the average hiker. If I didn't add enough, we wouldn't have any better reading than using the first approach. So, in the end I decided to only count hills that rose or dropped 25 feet in elevation or more. This helped to smooth out the data and give us a more meaningful elevation gain figure.
While calculating the elevation for each hike I realized that when you make a descent on the way to your destination you have to regain that elevation in the next climb and so the descent actually becomes an additional gain on your way to the destination. Also, on the return journey each of those descents you experienced becomes an additional climb on the way back. So I carefully calculated each hike both for the elevation gained and lost on the way to the destination and for the return journey to come up with my elevation gain figures.