While the transport capacity of a ski area can be easily measured on the basis of lift data, the determination of the area is more complicated. Without a doubt, pistes that are groomed every night are particularly comfortable. But what about pistes that are only groomed episodically? Or ski routes that only get to see a snow groomer from time to time or never at all? How is the open terrain to be evaluated, where skiers also make turns and take pressure from the organized ski area while putting their lives at risk?

If you want to compare areas of ski resorts in the Alps and in North America, the different philosophy of defining skiable terrain makes things more difficult. In North America, you can use the entire terrain within the ski area boundaries (boundary area), because it is entirely protected from avalanches (or areas are only opened if this is the case). In the Alps this only applies to pistes and ski routes. Nevertheless, there is no restriction between Montblanc and Dachstein to ski in the so-called open ski terrain or next to it, as this is only done at one's own risk - which is why relatively few skiers do so.

By weighting the various area categories differently, however, you can make them comparable. Of course, the daily groomed piste is considered 100 percent. With decreasing grooming intensity the weight decreases, even if the fun for some people in the ungroomed terrain between the trees rather increases. For the majority of skiers, however, such areas are not relevant and therefore provide only limited relief for the classic pistes. The figure shows the area categories and weights used to determine the relevant skiable area.

The following table illustrates the determination of the skiable area for eight different ski areas. Zero hectares of episodically groomed pistes means that all pistes are groomed daily - which is the standard in the Alps. The ski routes widespread in Switzerland and Austria are treated in the same way as the ungroomed pistes of North American ski resorts. The latter are mostly difficult pistes that are offered as moguls. For the ski routes, the width will be 20 metres and for the ungroomed slopes, the actual area will be taken into account.

Categories d) and e) do not exist in European ski resorts. Here they belong to the unsecured, open ski terrain. Since this terrain is skied on anyway, it is taken into account with a weight of five percent. In North America, the off-piste areas within the ski area boundaries are also secured. Some of these are developed areas (category d), as the off-piste areas are marked in treeless terrain or those in forests are cleared of vegetation (so-called glades). The undeveloped terrain (category e) is left in its natural state but protected from avalanches. Access to this terrain is partly controlled by gates.

The weighted skiable area is only included in the evaluation of the skiing comfort. In the calculation of the Skimiles the categories belonging to the developed area are taken into account (at 100 per cent each), since the total boundary area of the ski area already includes the undeveloped and open terrain and therefore this are already taken into account when calculating the Skimiles.