Our Guide to the 2025 UTMB Mont-Blanc

Ultra-Trail du Mont-Blanc—aka UTMB—isn’t just one thing. It’s the Spandex Superbowl, wrapped in Gore-Tex Mardi Gras, with a dash of Chafing World Cup. It’s a week-long festival of mountain racing that attracts thousands of runners to Chamonix, France.

What started as a stand-alone 171K (106-mile) race in 2003 has transformed into a weeklong acronym circus under the banner of UTMB Mont-Blanc. The alphabet soup of race names reference the tiny alpine villages in France, Italy, and Switzerland the races pass through. The epicenter is in Chamonix, France (elevation 3,400 feet) at the base of Mont Blanc—the highest summit in the Alps at 15,781 feet—where some of the races begin but all finish amid hordes of enthusiastic fans.

Beginning on August 25, the French village’s cobblestone streets will teem with compression-sock-clad competitors who will line up at one of the eight events throughout the week. The six smaller races (perhaps in prestige, rather than mileage, as in the case of PTL) lead up to UTMB, considered by many to be the sport’s crown jewel.

But if you’re in Chamonix, the races are just the tip of the glacier. Walk through town during the last week of August and you’ll find numerous fun runs, brand activations, parties, film releases, and new trail running shoe drops. If you’re a fan of the sport, it’s a who’s who of trail running athletes and personalities. And even if you’re not running one of the seven races, it’s still a fun time to be in Chamonix because there are hundreds of miles of trails to be run in between bouts of spectating, cheers, and chasing the races.

Here is a rundown of the week’s races.

UTMB: The Ultra-Trail du Mont-Blanc

The marquee and last event of the week-long series, UTMB completely circles its namesake summit in just over 100 miles with a whopping 32,808 feet of vertical gain—more than it would take to summit Everest from sea level. About 2,300 runners will attempt to traverse the course’s 10 alpine summits in under 46 hours 30 minutes.

Jim Walmsley became the first American man to win UTMB in 2023, but American women have crushed it in Chamonix since its inception. Krissy Moehl won the inaugural event in 2003, and again in 2009. Rory Bosio racked up two consecutive victories in 2013 and 2014, and Nikki Kimball claimed the title in 2007. Courtney Dauwalter won it in 2019, 2021, and 2023—the latter of which capped off an epic summer that also included wins at the Western States 100 and the Hardrock 100. Kate Schide continued the tradition in 2022 and 2024.

PTL: Petite Trotte à Léon

Perhaps UTMB’s most distinctive event, the PTL takes teams of two to three runners over 300K (186 miles) of rugged, unmarked terrain around Mont Blanc. Named for an adventurous French baker and hardcore volunteer, it takes many teams the allowed 151 hours to get to the finish line in Chamonix. The PTL begins on the morning of August 25 in Chamonix and the final cutoff is August 31 just before UTMB officially ends. The course changes every year and there is no official winner. The event is so challenging that finishing is judged as a win.

MCC: Martigny-Combe-Chamonix

The MCC is a 40K (24.8-mile) race for the “bénévoles” and “gens du pays,” the volunteers and locals who help with UTMB. One of the shorter races, it provides an accessible yet surprisingly challenging (7,500 feet of elevation gain) glimpse into the French Alps. This year’s MCC begins in Martigny on the morning of August 26.

TDS: Sur les Traces des Ducs de Savoie

The extra-technical TDS is the “cool-kids” race, historically attracting a who’s who of mountain runners from around the world. With the advent of the UTMB World Series Finals in 2022, which does not officially include TDS, this race has diminished in competitiveness and prestige a bit. However, it remains just as rugged. TDS traverses 148K (92 miles) from Courmayeur, Italy, to Chamonix around the Mont Blanc massif. This “mid-distance” (by UTMB standards) event hosts 1,600 runners, and has a 42-hour cutoff. The TDS begins on the afternoon on August 26 and the first finishers will arrive in Chamonix on the morning of August 27. No American has ever won TDS, but Hillary Allen ran a ferocious race and finished second in 2019.

YCC: Youth Chamonix Courmayeur

It’s like the Little League World Series, Europeanized. This two-day race format for kids ages 14-19 offers an opportunity for the next generation to test themselves on the sport’s biggest stage. Day 1 features a self-supported looped course through Courmayeur, and Day 2 is a time trail in Chamonix in which runners start slowest to fastest based on their times from the previous day. Past winners include Lucy Bartholomew (2016), who’s gone on two finish in the top 10 of UTMB twice. (She’s racing CCC this year.)

ETC: Experience Trail Courmayeur

The newest race to UTMB week, the ETC is a grueling 15K (9.3-mile) race from iconic village of Courmayeur, Italy, that includes a beastly 3,937 feet of total elevation gain in the heart of the Italian Alps. This year’s ETC will begin on the afternoon of August 27 and runners will have four and and a half hours to complete the race.

OCC: Orsières-Champex-Chamonix

Probably the closest thing UTMB has to an entry-level race, this 55K (34 miles) is a testing ground for many future UTMB competitors and top 50K racers from around the world. It sends runners from Orsières, Switzerland, to Chamonix during the daylight hours. The route climbs over 11,000 feet as it winds through the Swiss Valais region with a 14-hour-30-minute cutoff. The OCC begins on the morning of August 28 and the first finishers will arrive in Chamonix by early afternoon.

CCC: Courmayeur-Champex-Chamonix

Previously seen as the “little sister of the UTMB,” CCC has become a respected race in its own right with a demanding 101-kilometer course that ascends over 20,000 feet. It just about covers the last 100K (62 miles) of the UTMB course, which offers an in-depth preview for many runners with UTMB dreams. Historically, Americans have been successful at CCC, with notable American victories by Clare Gallagher, Hayden Hawks, and Zach Miller. This year’s CCC will begin at 9 A.M. local time on August 30 in Courmayeur, Italy, and the first runners are expected to arrive in Chamonix later that evening, just a few hours after the UTMB runners depart from downtown.

Race Schedule

How to Watch UTMB Mont-Blanc

All three premiere races, OCC, CCC, and UTMB, will be available to watch for free on Outside TV. If you’re sleeping and miss the action live, no sweat. Outside+ members will also be able to watch on demand after the finish anytime, on any device.

You can also follow the action of all eight races, as well as the progress of any particular runner, by checking the livetracker.

Watch on Outside TV