Daylight Hiking Window Calculator

Check whether your planned hike will finish before dark, given your start time, local sunset time, a safety buffer, and your expected hike duration.

Start Time

Sunset Time

Safety Buffer (minutes)

Expected Hike Duration (hours)

How the window is worked out

Everything is converted to minutes past midnight, and the buffer comes off the daylight before your hike is compared against it:

available = sunset - start - buffer
margin = available - hike duration
on track when margin is 0 or more

The defaults show it: a 09:00 start against a 19:30 sunset is 630 minutes, less the 30 minute buffer leaves 10.00 hours, and an 8 hour hike finishes with a 2.00 hour margin. Push the hike to 10.5 hours and the card flips to "At risk" with a 0.50 hour shortfall.

Filling in the times honestly

Nothing here is looked up for you. Get sunset for your date and trailhead on the morning you go - it moves two to three minutes a day, so a figure copied from last week can be a quarter of an hour out in autumn.

Duration should already include stops. Lunch, photos, water filtering and navigation checks add 20 to 30 percent to moving time.
A 30 minute buffer is thin. Sixty to ninety is more usual for a full day, and more again for a group or an unfamiliar trail.
Sunset is not darkness. Usable twilight adds 20 to 30 minutes in mid latitudes, but an east-facing valley or dense forest goes dark well before the published time.

This is a same-day sum. A sunset earlier in the clock than your start gives a negative daylight figure rather than rolling over midnight, so use it for day hikes only - and carry a head torch whatever the margin says.

Frequently asked questions

How long after sunset does it stay light enough to hike?

About 20 to 30 minutes of civil twilight in mid latitudes, longer at high latitude and shorter near the equator. Under tree cover, assume less.

What buffer should I use before dark?

An hour for a day hike, and two if the group is mixed or the route is new to you. The buffer is what absorbs a wrong turn, a blister or a slower partner.

What if the calculator says I am at risk?

Start earlier, shorten the route, or plan a turnaround time - fix a clock time at which you head back whatever you have reached. Pushing on with a head torch is the last option, not the plan.