Itineraries
GR20 in 12 days: which stages to combine?
Finishing the GR20 in 12 days means merging four pairs of official stages out of sixteen. Our data — the same numbers behind the site's planner — points to the four gentlest combinations, and above all to the ones you should never attempt. Here is the plan, merge by merge, with the figures.
The principle
Merge the gentle, never the hard
On our difficulty scale (10 = maximum), a "normal" official GR20 stage sits between 3.5 and 7.4 — the hardest natural stage, stage 6, reaches 7.44. Merging two consecutive stages therefore always creates a day at the level of the toughest natural stages, or beyond. The rule is simple: merge the gentle, never the hard. By doubling four well-chosen, non-overlapping pairs — the gentlest on the route — you go from 16 to 12 days without any single day exceeding a difficulty of 8.34. The four merges below are exactly those; every other combination scores higher, sometimes maxing out the scale entirely.
The plan
The four recommended merges
Stages 2+3: Ortu di u Piobbu → Ascu Stagnu
12.2 km, +1,384 m, -1,456 m, difficulty 7.55. Short on paper, dense on the ground: you drop towards Carrozzu, cross the Spasimata slabs and footbridge, then climb back up to Haut-Asco. The merge works because the distance stays very contained — the shortest of our four recommendations — with serious but well-spread elevation change. One caution: the Spasimata slabs are best crossed in the morning on dry rock, so start early and keep something in reserve for the final climb to Ascu Stagnu.
Stages 8+9: Petra Piana → Vizzavona
20.0 km, +1,087 m and above all -2,009 m of descent, for a difficulty of 7.92. This is the classic merge for hikers in a hurry: Petra Piana to Onda, then the long descent to Vizzavona, with its train station, supplies and a real bed. It works because the profile tilts massively downhill and Vizzavona offers genuine recovery afterwards. One caution: that much descent in a single day takes a toll on the knees — poles are essential, and don't be fooled by how easy downhill looks late in the day.
Stages 13+14: Usciolu → Asinau
20.8 km, +869 m, -1,074 m: at 7.44, this is the gentlest merge on the entire route — exactly the level of stage 6, the hardest natural stage, but no higher. The terrain helps: from Usciolu the trail crosses the plateau via A Matalza before reaching Asinau, on ground far more rolling than the north. One caution: the distance is still real, and on these southern ridges afternoon storms demand an early start — a gentle profile is no excuse to leave late.
Stages 15+16: Asinau → Conca
28.3 km: the longest day of this plan, but only +719 m against -2,014 m — a massively descending profile, difficulty 8.34. This is the merge that ends the traverse in style: Bavella, I Paliri, then the long plunge down to Conca and the maquis. It works because there is almost no climbing left; all the effort goes into distance and descent. One caution: it is the toughest of the four recommended merges, and it comes at the end of the traverse on worn legs — knees take the hit, so bring poles and water for a full day out.
Off limits
What you never merge
Six merges saturate our scale at 10/10: stages 1+2, 5+6, 6+7, 9+10, 10+11 and 11+12. The logic never changes: anything touching stage 6 — the longest on the GR20 at 24.8 km — or stage 1, with its +1,376 m of relentless climbing, produces 30 km days or days with +1,900 m of ascent. The same goes for the block from stages 9 to 12, in the heart of the southern half: those days already run back to back without respite, and doubling them creates outsized efforts. A natural stage never exceeds 7.44 in difficulty; these merges blow through the ceiling. Don't attempt them, however fit you are.
Nuances
Depending on your shape — and better than merging
Depending on your shape, two other merges are worth discussing: stages 12+13 (21.8 km, +905 m, difficulty 7.80) and stages 7+8 (18.3 km, +1,247 m, 8.32) — harder than our four picks, but feasible for well-trained hikers. Stages 3+4 (difficulty 9.76), on the other hand, remain inadvisable: that is the most alpine day on the route. Above all, pure stage merges are not the only option: intermediate stops — the Ballone, Vaccaghja and Croci bergeries — allow finer splits than refuge-to-refuge, and that is exactly what the planner computes.
Merging can also be decided the evening before, based on the forecast and the state of your legs — nothing forces you to lock the plan in before you set off.