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The planner

Can I do this hike?

Most planners give you a cheerful total and stop. This one runs the honest method: a base estimate, the corrections that make a real day slower, and a turnaround worked backwards from the light, so the answer is a plain go or no-go rather than an optimistic number.

The route

Lac Blanc figures are the official Chamonix Tourist Office numbers. Edit any field to plan your own.

You, today
The daylight

The verdict keeps a 45-minute buffer before the light goes. Don’t know the sunset? Work it out with the turnaround & daylight tool.

The honest read

There's time for this

A realistic 3 h 12 m car to car. Starting at 09:00, you finish around 12:12. That leaves about 7 h 03 m before your buffer — time in hand.

Where the time goes

Base moving time (Naismith)+2 h 14 m
Fitness — steady day-hiker+20 min
Steep / rough descent+17 min
Breaks and faff+21 min
Realistic total3 h 12 m

Your turnaround

Latest safe start
16:03
Turn around by (at the high point)
17:49

Turnaround assumes the descent is roughly 1 h 26 m of the day (an estimate). Reach that time and you turn around, wherever you are.

This is a planning estimate, not a promise. The method behind it is in how long a hike really takes and Naismith’s Rule.

How the verdict is worked out

The planner runs the same honest time method as the calculator, then does the part most tools skip: it checks the clock against the light. It starts from Naismith’s Rule and layers on the corrections a real day brings, fitness, pack, a steep descent, altitude and breaks, to reach a car-to-car time you can plan against.

Then it works backwards from sunset. Keeping a 45-minute buffer before the light goes, it finds the latest safe start and the moment you must turn around, whether or not you have reached the top. The answer comes back as a plain read: there is time for this, it is tight, or not on this start.

The full method and its sources are in how long a hike really takes. Reading a route before you plan the time? Start with how hard a hike really is, or browse the route guides.