From Sainte-Marie-de-Campan (west), the ascent is 12.8 km (8.0 mi) in length, gaining 642 m (2,106 ft) in height, at an average of 5%.

In comparison with its neighbour, the Col du Tourmalet, this is considered an "easy" climb, with only the last five kilometres, at about 8%, being difficult.

[3] On both sides of the Col de l'Aspin mountain pass cycling milestones are placed every kilometre.

Such signposting for cyclists has become common in most major mountain passes in the French Pyrenees and Alps.

The pass has been part of the Tour de France 71 times,[4][5] largely because it is the middle link in a chain of three road climbs, the other links being the Col du Tourmalet (2,115 m (6,939 ft)) and Col de Peyresourde (1,569 m (5,148 ft)).