23km: an historic race
23km du Mont-Blanc
Created in 1979, the Cross du Mont-Blanc will celebrate its 46th edition in 2025. This popular race, whose route has barely changed since its creation, will take you in the tracks of the discipline's pioneers, surrounded by a breathtakingly beautiful panorama!
To take part in this race, it is recommended to have good mountain running experience, to be comfortable on all types of terrain and to be self-sufficient for several hours. Please note that a runner with an UTMB index inferior to 270 points has very little chance to finish the race, so it is recommended to register for another Mont-Blanc Marathon race.
Race info
23km semi-autonomous trail run
1680m D+ / 870m D-
Open to Espoirs and above
Limited to 2,000 runners
6 starting waves
Maximum time: 6 hours
2 full feed stations + 1 finish feed station
Interactive map PDF map Estimated passage times Race profile
Number withdrawal
Pick-up of race numbers for the 23km will be by appointment only, at the Espace EMC2 on Place du Mont-Blanc (Chamonix):
- Thursday June 26, 2025 from 9am to 9pm,
- Friday June 27, 2025 from 9am to 9pm.
Runners must present photo ID and a race bag containing all compulsory equipment, to enable a timing chip to be fitted and equipment to be checked.
No bibs will be issued to runners without their compulsory equipment and identity papers. No race numbers will be distributed on the Saturday morning before the start of the race.
Compulsory equipment
- Cell phone in working order.
- Minimum 0.50-liter water supply.
- Waterproof jacket with hood (gore-tex type) adapted to your size.
- Survival blanket (140cm x 200cm).
- Tumbler.
- Whistle.
- Cash.
Recommended equipment
- Cap.
- Tights.
- Gloves.
Time barriers
The time limits given below are for guidance only. In the event of bad weather conditions, and for safety reasons, the organization reserves the right to stop the event in progress or to modify the time limits. All decisions will be taken by the race jury.
- Montroc feed station (km 11.4): start time of last wave + 2h30.
- La Flégère feed station (km 18.4): start time for last wave + 4h30.
- Maximum race time - Chamonix Planpraz (23km) : Start time for each wave + 6h.
The arrival of a runner at a time barrier after the time barrier has been applied will result in disqualification. The lower right-hand corner of the race number will be "cut out" by the station manager and the runner will be asked to return to Chamonix. Should the runner wish to continue on the course, his or her number will be collected by the station chief and the runner will no longer be considered a participant in the Mont Blanc 90km, and will therefore no longer be under the responsibility of the organizer. Anyone disrespecting the volunteers responsible for enforcing the time limits will be banned from all Mont Blanc Marathon events.
Maximum race time
Runners crossing the finish line after the maximum race time will not be classified and therefore not considered as finishers. This maximum time is calculated according to the start time of your wave.
23km du Mont-Blanc: maximum race time 6h00
The organizers would like to draw runners' attention to the fact that, depending on the systems and settings used, GPX tracks may give different results for race distances and gradients.
Runner bags
For runners of the Kilomètre Vertical and 23km du Mont-Blanc, who make a request at the time of registration, the organizer offers to transport their belongings to the race finish in Planpraz. Only one bag per runner can be requested. This will be provided by the organizers at the time of number collection, provided that the runner has requested it at the time of registration.
The organizer declines all responsibility in the event of loss, theft or damage to participants' personal belongings in the bags (it is recommended not to place valuables in the bags). Participants' belongings will be transported to the finish only if they are in the bag provided by the organizer.
In the event of a runner abandoning the race, the bag containing his or her belongings will be returned to Race HQ located at the Club des Sports de Chamonix, 99 avenue de la Plage, 74400 Chamonix, within a minimum of one hour of the abandonment being reported to Race HQ.
No lightening bags are available for the other races of the Mont-Blanc Marathon. It is the responsibility of each runner to make their own arrangements for transporting or storing their belongings.
