Hiking the Tour du Mont-Blanc with children is entirely possible, provided you rethink the stage breakdown, accept using valley transport and aim for enjoyment rather than performance.
From what age?
From the age of 8 to 10, a child who is used to hiking can walk 4 to 5 hours a day with 500 to 700 m of ascent, several days in a row. Any younger, and it is better to pick a few day walks from one valley rather than the full Tour.
The rule that works: the day should stay shorter than what the adults could manage, and include at least one appealing « goal » — a lake, a herd of animals, a zip wire, a refuge with a big shared table.
Breaking the Tour down differently
Over 12 to 14 days, stages come to around 4 hours of walking and become accessible. Valley transport (the Les Contamines shuttles, the Val Veny bus, the La Flégère gondola) lets you shorten the longest days without giving up on the Tour.
The most suitable stages: Les Houches – Les Contamines, the Val Veny as far as Courmayeur, La Fouly – Champex, and the traverse of the south balcony between La Flégère and Planpraz.
Booking and sleeping in refuges with children
Always tell the refuge the children's ages when you book: some have small rooms or 4-bed dormitories, which are far more comfortable for a family. Book early, as those beds go first.
Think about meals too: most refuges will adjust portions, but a snack during the day remains essential to avoid the end-of-stage energy dip.