01
Plan outdoor time and safety margin
Descent before sunset, start time, headlamp runtime, altitude-adjusted temperature, and group pace are calculated with conservative safety margins.
Headlamp runtime calculator
Combines battery capacity, current draw, and a reserve percentage to estimate conservative runtime hours against your planned night hike time.
This reference helper calculates inputs in the current browser only. For decisions requiring official data, check the latest guidance from the relevant authority.
Headlamp runtime calculator
02
Field judgment and forecasts come first
Weather, trail condition, fitness, and gear matter more than the formula. If the margin is tight, shorten the plan, turn back, or add backup gear.
Frequently asked questions
How much sunset buffer should I keep?
It depends on terrain and group size, but enter a separate safety buffer. If the result is negative, shorten the route or start earlier.
Whose pace should define group speed?
Use the slowest member. Planning from the faster average underestimates rest, waiting, and late-day risk.