90km du Mont-Blanc is a 90km ultra marathon in Chamonix, France. Distance: 90km. Elevation: 5,800m D+. Difficulty: challenging (Challenge Rating 57/100). DNF rate: 20%. Time limit: 24h. Surface: trail. Established 2019.
90km du Mont-Blanc
Chamonix, Haute-Savoie, France
"90km with 5,800m climbing around Chamonix."
A 90km mountain ultra with 5,800m vertical in the Chamonix valley.
The Course
A 90km loop through the French side of the Mont Blanc massif, starting and finishing in Chamonix. The route climbs through the Contamines-Montjoie valley, crosses the Col du Bonhomme (2,329m) and Col de la Croix du Bonhomme (2,433m), then returns via the dramatic balcony trails above the Chamonix valley. The terrain is classic Haute-Savoie: well-maintained Alpine paths, steep rocky switchbacks, and flower-filled meadows between the brutal climbs. Views of the Glacier des Bossons and Aiguille du Midi are constant companions.
mountainous
loop
8
Runner Experience
Standard aid station support with food, drinks, and basic medical assistance at regular intervals.
Mountain village finish with local food, drinks, and a relaxed post-race atmosphere. The setting rewards the effort.
Race Day Weather
14°C
4° – 22°
55%
30%
Alpine summer — warm valleys, cold passes.
Stats & Records
2019
600
16:00:00
Entry
€120
December
days
Lore & Trivia
The 90K du Mont Blanc occupies the space between CCC and UTMB in the Chamonix race family — long enough to be a serious alpine test, short enough that experienced runners can push the pace rather than merely survive. The course traverses the French side of the Mont Blanc massif through Contamines-Montjoie, over the Col du Bonhomme, and back to Chamonix. For many runners, it's the perfect UTMB stepping stone — a race that builds confidence for the full loop without the 46-hour time commitment.
- ▸ Part of the famous Marathon du Mont-Blanc week.
- ▸ The course passes under Mont Blanc, Western Europe's highest peak.
- ▸ 5,800m climbing in 90km — one of the steepest per-km ratios.
- ▸ Established in 2019.
- ▸ Total elevation gain: 5800m.
The 90K gives you Mont Blanc without the 170km of destruction. You can actually enjoy the Alps.
Notable Editions
Record Depth of Field
The 2019 edition attracted the deepest competitive field in the race's history, with multiple UTMB podium finishers using the 90K as preparation for the main event later in the week.
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Frequently Asked Questions
How long is 90km du Mont-Blanc? +
90km du Mont-Blanc is a 90km (90km) ultra marathon with 5,800m of elevation gain. The course is loop on trail terrain.
How hard is 90km du Mont-Blanc? +
90km du Mont-Blanc is rated challenging with a Challenge Rating of 57/100 (Challenging). The DNF rate is 20%. Runners have 24 hours to finish.
What is the weather like at 90km du Mont-Blanc? +
Average temperature is 14°C (range 4°C to 22°C) with 55% humidity and a 30% chance of rain. Alpine summer — warm valleys, cold passes.
Are crew and pacers allowed at 90km du Mont-Blanc? +
Crew access is allowed. Pacers are not allowed. Mandatory gear is required.
What is the average finish time for 90km du Mont-Blanc? +
The average finish time is 16:00:00. About 600 runners finish each year. The DNF rate is 20%.
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