Via Ferrata Grade Scale (SAC)

K1 (very easy) Generally well marked, and secured where necessary. Security cables / attachment points comfortable to use. Good natural steps; where these are missing, hewn stairs, short ladders and iron steps. Any exposed passages are fitted with cables or chains / rope for handrails rails). Experienced mountaineers may choose not to clip in. Examples: Alpbachschlucht, Simmeflue

K2 (easy) Already entering some steep climbing terrain, but the route is very secure. Steep or vertical passages are fitted with ladders and/or iron steps. Steel cables and chains secure the climber, even in less difficult terrain. Ferrata set strongly advised. Examples: Eiger-Rotstock, Rigidalstockgrat,

K3 (moderate) Longer stretches in steep terrain, climbing sections of grade III, still very well secured. Some technical climbing, but nothing that requires particularly strong arms. Ferrata set necessary. Examples: Tälli, Graustock, Angelino Monte Generoso, Farinetta 1

K4 (difficult) Steep to vertical rock, even some well secured overhanging sections. In many cases the route feels exposed, natural steps and handholds are often small. Steep terrain with continuous steel cables to attach to. Arm strength required. Artificial aids (iron steps, handholds) on hardest sections. The french style “sport via ferratas” are an exception: on some you may barely touch the rock at all, but climb an intricate series of iron rungs, crazy ladders, and even ‘spiders webs’, with maximum exposure. Examples: Allmenalp, Gantrisch, Tour d’Aï, Echelles de la Mort, Farinetta 2

K5 (very difficult) Via ferratas in the most difficult and consistently steep terrain. Upper body strength and good technique, as well as good fitness are prerequisites. Long, persistently demanding and therefore very strenuous. Vertical or exposed terrain may only have cables for safety, but little in the way of artificial steps, these are reserved only for places that would other wise be impossible to cross. For experienced climbers who are in good shape. Examples: Evolène Abschnitt 3, Greitspitz, Rochers de Naye

K6 (extremely difficult) Via ferrata for gymnasts / athletes with bulging biceps and nerves of steel. Long sparsely secured gymnastic circuits that require real stamina. Climbing/approach shoes may be useful. Additional security to be provided by rope/ belaying (recommended) Examples: Leukerbadner 2. Teil, Piz Trovat 2, Farinetta 3

Other important factors that constitute the grade:

• - Altitude: valley/ low mountain range/ high Alps?
• - Terrain style: sheltered by forest/ short steps through alpine meadows/ steep cliffs/ ridges.
• - Length and exposure of the route—commitment value.
• - Route characteristics: type and regularity of attachment points/ safety cables.
• - Ascent plus descent i.e. total route length
• - Path used for approach and descent: paved paths/ gravel footpath/ pathless
• - Orientation: is it well marked?

All these factors result in the overall rating from K1 (very easy) to K6 (extremely difficult). 

Source: https://www.sac-cas.ch/fileadmin/Ausbildung_und_Wissen/Sicher_unterwegs/Sicher_unterwegs_Klettersteig/2020_Via_Ferrata_Grade_Scale.pdf