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A grassy slope with scattered pines near Chamonix, under jagged peaks and pink clouds
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Marathon du Mont-Blanc course maps and aid stations

Five races from the center of Chamonix, from a 3.8 km Vertical Kilometer to a 90 km that crosses into Switzerland.

June 24 to 27, 2027 Chamonix, Haute-Savoie, France

The Marathon du Mont-Blanc is a long weekend of trail races in Chamonix, run by the Club des Sports de Chamonix. It started in 1979 as the Cross du Mont-Blanc, a 23 km to Planpraz, and added the 42 km in 2003. About 10,000 runners now come each year for eight races. The 2027 edition runs June 24 to 27.

The 42 km heads up the valley to Le Tour, climbs the Aiguillette des Posettes, drops to Vallorcine and comes back along the balcony above Chamonix, with the Mont Blanc massif across the valley. The 90 km goes over Le Brévent, into Switzerland at Emosson and back over Tête de Balme, then finishes by way of Les Bois, Montenvers and Plan de l'Aiguille. The 23 km climbs to Planpraz, the 10 km stays low near Chamonix, and the Vertical Kilometer goes straight up to Planpraz.

The maps show the 2026 courses and aid stations: the 2027 ones aren't out yet. The 90 km asks you to carry a phone with a plan that works in France and Switzerland. Download the map before you go, and your phone's GPS shows where you are whichever network you're on.

This is an unofficial guide: Goat Maps isn't affiliated with Marathon du Mont-Blanc. Check the official site before you enter or race.

Marathon du Mont-Blanc course map

Every course's aid stations on the Goat Maps topo map. Each course has a map of its own further down.

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Marathon du Mont-Blanc courses

CourseDistanceClimbingStartTime limit
90 km88.8 km (55.2 mi)6,137 m (20,135 ft)24 h
42 km42 km (26.1 mi)2,540 m (8,333 ft)10 h
23 km23.5 km (14.6 mi)1,680 m (5,512 ft)6 h
10 km10 km (6.2 mi)325 m (1,066 ft)2 h 30 min
Vertical Kilometer3.8 km (2.4 mi)1,000 m (3,281 ft)

Marathon du Mont-Blanc 90 km

Both sides of the valley, from Le Brévent to Emosson in Switzerland and back by Montenvers.

Distance
88.8 km (55.2 mi)
Climbing
6,137 m (20,135 ft)
Time limit
24 h

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In 2026 the 90 km started at 4:45 on Friday morning in three waves ten minutes apart. The organizer's passage-time chart gives 88.8 km and 6,137 m of climbing, and those are the figures on this page; the race page says 88 km and 6,200 m. The first big climb, straight out of town, tops out at Le Brévent, 2,471 m, after about 10 km. The organizer says some trails are narrow and exposed, some sections can be under snow, and a lot of the race sits between 2,000 and 2,500 m.

The longest stretch without food is the 15.7 km from Planpraz to Le Buet: Flégère is only a time check, and there's no aid station on Tête aux Vents or at the Col des Montets. La Villaz has a fountain and Le Châtelard just a cutoff. Plan de l'Aiguille, 7.6 km from the finish, serves drinks only. Every cutoff counts from the start of the last wave; the 24 hour limit counts from your own. The organizer calls it a very technical race and says that below a UTMB index of 450 you have very little chance of finishing. In 2026, 65% finished.

aid stations

kmWhereCutoff
0Place du Triangle de l'Amitié, Chamonix
12.7Planpraz
18La Flégère 4 h 30 min
28.5Le Buet Crew6 h 30 min
35.1La Villaz (fountain) 8 h
40.6Emosson Crew10 h
44.7Le Châtelard (cutoff) 11 h
48.4Belleplace chairlift, Les Esserts
60.1Le Tour Crew15 h 15 min
69.7Les Bois Crew17 h 15 min
75.2Montenvers Crew19 h 45 min
81.2Refuge du Plan de l'Aiguille Crew21 h 45 min
88.8Place du Triangle de l'Amitié, Chamonix 24 h
Rocky outcrops and hazy ridges seen from the top of Le Brévent
Sies Kranen / Unsplash

Marathon du Mont-Blanc 42 km

Fast valley trails to Le Tour, then the Aiguillette des Posettes and the balcony back to Chamonix.

Distance
42 km (26.1 mi)
Climbing
2,540 m (8,333 ft)
Time limit
10 h

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The 42 km is the headline race, with 2,540 m of climbing. In 2026 it ran on Sunday. The first 13.5 km up to Le Tour are quick and rolling, followed by the steep, technical climb to the Aiguillette des Posettes, about 2,200 m, the course's main obstacle, and the descent to Vallorcine. The last third climbs from the Col des Montets to La Flégère and comes back along the balcony to finish in the center of Chamonix.

Cutoffs at Le Tour, Vallorcine and La Flégère count from the last wave's start, and you have 10 hours from your own. Below a UTMB index of 350, the organizer gives you very little chance of finishing. In 2026 Tove Alexandersson ran 3:55:07, the first woman under four hours and the first to finish ahead of the men's winner. The 42 km was part of the Golden Trail World Series from 2018 through 2024.

aid stations

kmWhereCutoff
0Place du Triangle de l'Amitié, Chamonix
13.5Le Tour Crew2 h 45 min
23.5Vallorcine Crew5 h 30 min
34.2La Flégère Crew8 h 30 min
42Place du Triangle de l'Amitié, Chamonix 10 h
A pointed snowy peak above forest in the Chamonix valley, framed by leaves
Torgeir ihle / Unsplash

Marathon du Mont-Blanc 23 km

The original 1979 race: up the valley to Montroc, then a climb to La Flégère and a finish at Planpraz.

Distance
23.5 km (14.6 mi)
Climbing
1,680 m (5,512 ft)
Time limit
6 h

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The 23 km is the race the event grew from, on a course the organizer says has barely changed since 1979. It starts from the paragliding area in Chamonix and runs up the valley through Les Bois, Le Lavancher and Argentière to the Montroc aid station at 11.4 km. From Tré-le-Champ it climbs to Le Béchar, drops through the Plagnolet woods, then climbs to La Flégère and traverses to the finish at Planpraz, about 2,000 m.

The race page calls it 23 km, with 1,680 m up and 870 m down. The distances here come from the organizer's 2025 passage-time chart, which measures 23.5 km to Planpraz and has the aid stations where the 2026 race page puts them. Cutoffs at Montroc and La Flégère count from the last wave's start, and you have 6 hours from your own.

aid stations

kmWhereCutoff
0Paragliding area, Chamonix
11.4Montroc Crew2 h 30 min
18.4La Flégère Crew4 h 30 min
23.5Planpraz 6 h

Marathon du Mont-Blanc 10 km

A loop near Chamonix with short, sharp climbs on singletrack.

Distance
10 km (6.2 mi)
Climbing
325 m (1,066 ft)
Time limit
2 h 30 min

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The 10 km is the race open to everyone, from the cadet category up, with 325 m of climbing. It loops out from the paragliding area and back, on cross-country ski trails and technical singletrack with short, steep ups and downs. There's no aid on the way, only at the finish, and the limit is 2 hours 30 minutes.

aid stations

kmWhereCutoff
0Paragliding area, Chamonix
10Paragliding area, Chamonix 2 h 30 min

Marathon du Mont-Blanc Vertical Kilometer

A 1,000 m time trial from the center of Chamonix to Planpraz.

Distance
3.8 km (2.4 mi)
Climbing
1,000 m (3,281 ft)

Take this course offline

Download its map in Goat Maps and you can find the next aid station without a signal.

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The Vertical Kilometer climbs 1,000 m in 3.8 km from Place du Triangle de l'Amitié to the finish at Planpraz, about 2,000 m. It's a time trial: in 2026 the first runner left at 4:00 PM on Friday and the rest followed every 15 seconds. The top section is exposed, with steps, cables and handrails like a via ferrata, and the organizer advises against it if you're afraid of heights. Poles aren't allowed.

aid stations

kmWhereCutoff
0Place du Triangle de l'Amitié, Chamonix
3.8Planpraz

Registration

Registration for 2027 opens between late October and early November 2026, in several phases, with the schedule still to come.

For 2026 the 90, 42 and 23 km split their bibs three ways. 10% went to Chamonix Valley residents coming by public transport, on foot or by bike, and 40% to runners committing to come by train or bus, both first come, first served. The other 50% went through a free lottery, where you could enter only one race. The 10 km and the Vertical Kilometer had no lottery, and kept 40% of their bibs for train and bus runners. Everyone pays a carbon offset based on the round trip from home. Train and bus runners upload their tickets before the race.

2026 entry cost 140 € for the 90 km, 80 € for the 42 km and 50 € for the 23 km. Entries can't be refunded or transferred, so take the cancellation insurance when you register if you want it. Every adult, French or not, needs an FFA licence or the FFA's online health prevention course (the PPS), done within three months of the race.

Getting to Chamonix

A river running between buildings in Chamonix, with snowy peaks above town
Patrick Boucher / Unsplash

Geneva airport is 88 km from Chamonix, and Flixbus runs daily between the two. By train, take the SNCF to Saint-Gervais-les-Bains-Le Fayet and change to the Mont-Blanc Express, or come from Switzerland on the Léman Express. The organizer pushes hard for the train: by its own count, 96% of the event's carbon footprint is travel to Chamonix.

Ask your accommodation for a carte d'hôte. With it the Mont-Blanc Express is free between Servoz and Vallorcine, so you can ride it to Argentière, Montroc or Vallorcine. You pick up your bib by appointment at the EMC2 room on Place du Mont-Blanc, with photo ID and your mandatory kit.

Following runners and crewing

The races are semi-autonomous: you carry what you need between aid stations, and outside help is allowed only within 100 m either side of one.

For the 42 km, supporters take the race shuttles or bus line 2 from Place du Mont-Blanc to Le Tour, the shuttles on to Vallorcine, then the train back and the gondola up to La Flégère. Montroc, on the 23 km, is reachable only by public transport. For the 90 km you can follow by shuttle or train to Le Buet, by the organizer's shuttle on to Emosson, by train and bus to Le Tour and Les Bois, and by the Montenvers train or the Aiguille du Midi cable car to the last two aid stations. In 2026 supporters got 50% off the Mont Blanc Multipass lift pass, and the Vertical Kilometer finish had free gondola access with a voucher from bib pickup.

Weather and what to carry

Snowy peaks and clouds reflected in Lac Blanc, above Chamonix
Raymond RUTJES / Unsplash

June in Chamonix, at 1,042 m, averages a high of 21.2 °C and a low of 7.5 °C, by Météo-France's 1981 to 2010 normals. It's also the wettest month of the year there, with 130.4 mm of precipitation. On the evening of June 27, 2026, bad weather made the organizer stop and then cancel the Duo Étoilé.

The 90 km's mandatory kit includes 1.5 liters of water, a hooded waterproof jacket, a warm long-sleeved layer, a headlamp with spare batteries, a survival blanket, a whistle, a cup, a bowl and spoon, and cash. The 42 km asks for a phone, 1 liter of water, a hooded waterproof jacket, a survival blanket, a cup, a whistle and cash. Poles are your choice on the long races, but if you take them you carry them from start to finish.

Marathon du Mont-Blanc aid stations and GPS coordinates

For crews and spectators: each place on the map in decimal degrees, latitude first. Paste them into any map app or add them as waypoints in Goat Maps.

  • Place du Triangle de l'Amitié, Chamonix

    1,036 m (3,399 ft)

    45.92357, 6.86920

  • Paragliding area, Chamonix

    1,036 m (3,399 ft)

    45.93013, 6.87645

  • Planpraz

    2,048 m (6,719 ft)

    45.93694, 6.85230

  • La Flégère

    1,894 m (6,214 ft)

    45.96019, 6.88585

  • Le Buet

    1,347 m (4,419 ft)

    46.01873, 6.91836

  • La Villaz (fountain)

    1,316 m (4,318 ft)

    46.04307, 6.93560

  • Emosson

    1,970 m (6,463 ft)

    46.06817, 6.93803

  • Le Châtelard (cutoff)

    1,148 m (3,766 ft)

    46.05959, 6.95709

  • Belleplace chairlift, Les Esserts

    1,651 m (5,417 ft)

    46.04678, 6.95708

  • Le Tour

    1,470 m (4,823 ft)

    46.00068, 6.94886

  • Les Bois

    1,090 m (3,576 ft)

    45.94095, 6.89980

  • Montenvers

    1,904 m (6,247 ft)

    45.93311, 6.91857

  • Refuge du Plan de l'Aiguille

    2,190 m (7,185 ft)

    45.90552, 6.88285

  • Vallorcine

    1,276 m (4,186 ft)

    46.03312, 6.93420

  • Montroc

    1,363 m (4,472 ft)

    45.99713, 6.93403

Marathon du Mont-Blanc FAQ

When is the Marathon du Mont-Blanc 2027?

June 24 to 27, 2027, in Chamonix. The day of each race hadn't been published when this page was checked. In 2026 the 90 km and Vertical Kilometer ran on Friday, the 23 km and 10 km on Saturday and the 42 km on Sunday.

How do you get into the Marathon du Mont-Blanc?

For 2026, half the bibs for the 90, 42 and 23 km went by free lottery and the rest, first come, first served, to runners committing to travel by train or bus or to Chamonix Valley residents. The 10 km and Vertical Kilometer had no lottery. Registration for 2027 opens between late October and early November 2026.

What UTMB index do you need for the Marathon du Mont-Blanc?

The organizer says runners below 450 have very little chance of finishing the 90 km, below 350 the 42 km and below 270 the 23 km. It recommends 160 for the 10 km and gives no figure for the Vertical Kilometer.

How hard is the 42 km du Mont-Blanc?

It has 2,540 m of climbing, and the organizer counts every 100 m of climbing as an extra kilometer, so it says the 42 km feels like 67 km. The limit is 10 hours, and 86% of runners finished in 2026.

Can you use poles at the Marathon du Mont-Blanc?

On the 90, 42 and 23 km, yes, but if you start with them you have to keep them the whole way, and you can't pick them up on the course. They're banned on the Vertical Kilometer and the 10 km.

Where does the Marathon du Mont-Blanc finish?

The 90 km and 42 km finish at Place du Triangle de l'Amitié in the center of Chamonix. The 23 km and Vertical Kilometer finish up at Planpraz, about 2,000 m, and the 10 km back at the paragliding area where it started.

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Updated . An unofficial guide, from the organizer's published information. Coordinates from the organizer's course and OpenStreetMap contributors. Photos from Unsplash. Organize a race? We help with course files.