Probably the most famous difficulty scale is the classification introduced in 1925 and later adopted by the UIAA (also known as the Welzenbach scale). It's a scale that indicates each difficulty with a Roman numeral.
Welzenbach classification system
I – First grade
II – Second grade
III – Third grade
IV – Fourth grade
V – Fifth grade
VI – Sixth grade
I - First grade (Easy)
It's the simplest way of climbing: you have to choose where to put your feet, and the hands frequently use holds, but only to keep your balance.
II – Second grade (Not very difficult)
You need to move one limb at a time so as to keep a firm position on three points of support, and the movements must be set up correctly. On the route holds and footholds are plentiful.
III – Third grade (Fairly difficult)
The rock is steep or even vertical, holds and footholds are less plentiful and it can sometimes call for strength in the legs and arms. The moves are not yet on forced lines.
IV – Fourth grade (Difficult)
Holds and footholds are rarer and sometimes small; the mountaineer needs good technique and a certain level of training.
V – Fifth grade (Tremendously difficult)
Holds and footholds are rare, small and hard to make out. The climbing demands technique and/or intense muscular effort. It's normally necessary to study the move beforehand.
VI – Sixth grade (Extremely difficult)
Holds and footholds are small and arranged so as to require a particular combination of well-studied movements. The rock can force you into very delicate friction climbing or decidedly tiring climbing on overhangs. It requires training and considerable strength in the arms and hands.
Please note that the Welzenbach scale has been extended: today it goes up to the tenth grade of difficulty. From the fifth grade upwards each grade can be refined with a + or a – sign, to give more detail within the scale.
For mountaineering difficulties there are other classification systems: British, French, American, Australian, etc... Each of these classification systems can be compared with the others through dedicated conversion tables.
Bibliography:
- Il grande libro della Montagna – The Mountaineers – Mondadori
- Il manuale dell’Alpinista – Giancarlo Corbellini – Piemme Pocket
- www.montagnapertutti.it
For paths without climbing see the hiking difficulty scale.