Ultra-Trail du Mont-Blanc is a 171km ultra marathon in Chamonix, France. Distance: 171km. Elevation: 10,000m D+. Difficulty: brutal (Challenge Rating 67/100). DNF rate: 35%. Time limit: 46h. Surface: trail. Established 2003.
Ultra-Trail du Mont-Blanc
Chamonix, Haute-Savoie, France
"The world's most prestigious mountain ultra. 171km around Mont Blanc through three countries with 10,000m of climbing."
The defining mountain ultra — a 171km loop around Mont Blanc through France, Italy, and Switzerland with 10,000m of vertical gain.
The Course
A complete loop around Mont Blanc, passing through France, Italy, and Switzerland. The course traverses alpine passes, glacial valleys, and mountain villages. Extreme vertical gain and technical descents make this one of the most demanding mountain ultras in the world.
mountainous
loop
11
2,537m
6
Runner Experience
UTMB-standard aid stations with hot food, drinks, medical support, and drop bag access at major checkpoints.
A legendary finish line atmosphere. Ultra-Trail du Mont-Blanc is a bucket-list race with celebrations that match its reputation.
Race Day Weather
12°C
2° – 22°
65%
40%
Alpine weather — highly variable. Can be warm and sunny at valley level while snowing at the passes. Night temperatures drop sharply at altitude.
Stats & Records
2003
1,800
36:00:00
19:01:56
Kilian Jornet (2022)
22:30:54
Courtney Dauwalter (2023)
Entry
€350
December
instant
Lore & Trivia
Ultra-Trail du Mont-Blanc is the World Cup final of trail running. A 171km loop around the Mont Blanc massif through France, Italy, and Switzerland, climbing 10,000m through some of the most spectacular mountain terrain on earth. Founded in 2003 by a group of passionate trail runners, UTMB has grown into a global phenomenon — 10,000 runners from 100+ countries apply; 2,500 start. The race begins in Chamonix at 6pm on a Friday and the best runners return 20 hours later; the back of the pack may take 46 hours. The route passes through Courmayeur, Champex-Lac, and Argentière, crossing high alpine passes by headlamp while the Mont Blanc massif looms overhead in moonlight. UTMB has become more than a race — it's a festival, a qualifying ecosystem (the UTMB World Series spans 40 countries), and the proving ground where trail running's biggest names are made. Kilian Jornet, Jim Walmsley, François D'Haene, Courtney Dauwalter — the sport's legends have all been defined by their UTMB performances.
- ▸ The loop circles the entire Mont Blanc massif through three countries: France, Italy, and Switzerland.
- ▸ 171km with 10,000m of elevation gain — equivalent to climbing from sea level to the summit of Everest and back.
- ▸ Over 10,000 runners from 100+ countries apply each year; roughly 2,500 start.
- ▸ Runners need qualifying points from other UTMB World Series races to enter.
- ▸ The race starts at 6pm Friday from the centre of Chamonix — the atmosphere is electric.
- ▸ The UTMB World Series now spans 40+ countries with qualifying events on every continent.
- ▸ Elite runners finish in under 20 hours; the cutoff is 46 hours and 30 minutes.
- ▸ The route passes through Courmayeur (Italy) and Champex-Lac (Switzerland) before returning to Chamonix.
UTMB is where you find out who you really are. The mountains don't care about your training plan.
When you come over the Col de Voza and see the lights of Chamonix below, 168 kilometres behind you — that's the moment. That's why we do this.
Notable Editions
The First UTMB
722 runners started the inaugural Ultra-Trail du Mont-Blanc. Only 67% finished. The race immediately established itself as the defining event in European mountain running.
Walmsley Finally Wins
After years of heartbreak at UTMB — including a famous 2017 DNF when he led by 20 minutes and collapsed — American Jim Walmsley finally won in 19:37:43, exorcising years of demons on the Mont Blanc loop.
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Frequently Asked Questions
How long is Ultra-Trail du Mont-Blanc? +
Ultra-Trail du Mont-Blanc is a 171km (171km) ultra marathon with 10,000m of elevation gain. The course is loop on trail terrain.
How hard is Ultra-Trail du Mont-Blanc? +
Ultra-Trail du Mont-Blanc is rated brutal with a Challenge Rating of 67/100 (Demanding). The DNF rate is 35%. Runners have 46 hours to finish.
How do I enter Ultra-Trail du Mont-Blanc? +
UTMB Index qualification through UTMB series races. Must accumulate sufficient running stones.. Entry is by lottery. Entry costs €350. with a maximum of 2300 starters.
What is the weather like at Ultra-Trail du Mont-Blanc? +
Average temperature is 12°C (range 2°C to 22°C) with 65% humidity and a 40% chance of rain. Alpine weather — highly variable. Can be warm and sunny at valley level while snowing at the passes. Night temperatures drop sharply at altitude.
Are crew and pacers allowed at Ultra-Trail du Mont-Blanc? +
Crew access is allowed. Pacers are not allowed. Mandatory gear is required.
What is the course record for Ultra-Trail du Mont-Blanc? +
The men's course record is 19:01:56 set by Kilian Jornet in 2022. The women's course record is 22:30:54 set by Courtney Dauwalter in 2023.
What is the average finish time for Ultra-Trail du Mont-Blanc? +
The average finish time is 36:00:00. About 1,800 runners finish each year. The DNF rate is 35%.
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