The identity of the course

UTMB (Ultra-Trail du Mont-Blanc) starts in Chamonix, France, and returns to Chamonix. It is not an out-and-back in a single valley: the route circles the Mont Blanc massif on mountain trails and crosses Italy, Switzerland and France. Starting and finishing in the same town does not make it a large road marathon; the borders, valleys and passes in between define it as a high-mountain ultra.

This page pins the 2026 edition, version 2026-utmb-mont-blanc. The organiser's 2026 stat block lists 174 km and 9,700 m of positive elevation gain. Treat these as rounded official statistics, not measurements to the metre.

What a high-mountain course implies

Distance and climb are only the entrance. The difficulty of a mountain ultra also comes from altitude change, running through the night, weather windows and the spacing of aid stations — none of which can be read from a simplified track. This page provides no segment-by-segment elevation profile and does not label aid stations, cut-off times or pass names, because those details change with each edition and official announcement, and no authoritative, redistributable dataset supports them here.

What can be confirmed is this: the route is a three-country loop, it starts and finishes in Chamonix, and the official distance and climb are the rounded values above. Training plans, pace targets and equipment lists should follow the organiser's rules and technical material for the current year.

Same town at both ends is not a simple course

Chamonix is both the departure point and the finish, which allows accommodation to be concentrated — and makes it easy to underestimate the course. A loop passes through several valleys with different weather; conditions at altitude can be completely unlike those in town. Prepare clothing for both low and high altitude, and treat a head torch, spare batteries and emergency warmth as a separate checklist.

For fuelling, see the long-run fuelling and recovery day entries on this site. They offer general principles and do not replace the organiser's mandatory equipment and aid-station information.

Why this site does not host a track

The organiser publishes an official GPX download on its 2026 race page. This page marks geometryAccess as official-link: it links to that file but does not bundle or redistribute it, draws no simulated route and does not pass off an illustration as real geometry. The map anchor sits at the Chamonix start only, to locate the event on the globe.

Only if the organiser later grants explicit redistribution permission will this site add a local track, its licence and attribution, and update the content digest.

Where to go next

• Use the pace calculator to understand what "174 km" means as an average moving speed for different finish targets.
• Use the track viewer to process your own activity files; uploads stay in your browser.
• Before race day, check the organiser's technical material for route changes, aid stations and mandatory equipment.

Sources and reuse

This text was prepared by the RunMap editorial desk from the organiser's 2026 public pages and is licensed CC BY 4.0. The event name, official marks, official route text and official GPX remain the property of the organiser; this page's original explanatory text is CC BY 4.0. The track is linked from the organiser, not redistributed here.

Sources

• The official UTMB event page: 2026 route, the 174 km distance, 9,700 m of climb, and the crossing of France, Italy and Switzerland.

The exact links appear in the source list at the bottom of the page.