In this section you will find definitions and explanations of various measures used on These include Altitude, Primary factor, Secondary factor, Vertical metres, and Distance.

My sources for stating a mountain's measures are several; for Norwegian mountains I tend to rely on Statens Kartverk. In some rare cases the number shown on maps are definitely wrong; a typical example is when the height shown on the map is stated for a trigonometric point, which clearly is not located at the summit. In these cases I rely on my personal GPS measurements and/or observations on-site and/or other sources.
For countries outside Norway I use whatever information I can get hold of; printed maps, digital maps, personal GPS measurements, and information on the Internet.
A hike's distance and number of vertical metres I usually find by analysing the GPS tracks.

Altitude (alt.)

I am using both "altitude" and "height" as the term to describe how high a point is above sea level.

Primary factor (PF)

The "simple" definition of primary factor is "the least vertical distance you have to descend in order to get to a higher point".
Primary factor, often called prominence, is crucial in order to defined whether a given point is a mountain or not. If you assume a long ridge with a lot of bumps on it you are likely to wonder how many mountains there are along this ridge; primary factor is the measure to apply to find the answer. If you have to descend at least 100 vertical metres from a given bump in order to get to a higher point then the bump in question can be regarded as an independent mountain. In some areas of the world a primary factor higher than 100 metres is used to define the list of independent mountains.
As a rule of thumb you can assume that the higher the primary factor the better the view, but there are definitely exceptions.

Secondary factor (SF)

The secondary factor of a mountain is the horizontal distance from the mountain's summit to the nearest point of equal altitude.
If the Secondary factor of a mountain is high then there is a long distance to another piece of land obstructing your views, and hence your are likely to see a large area of land from this mountain.


Vertical metres (vm)
The total number of vertical metres ascended. For a round-trip this will include the vertical metres for both the ascent and the descent (if any).

Distance (dist.)

This is the horizontal distance hiked.