How to use
- Enter the full out-and-back distance in miles and the pace you expect in minutes per mile.
- Enter the start time and the sunset in 24-hour time. A time field does this for you.
- Enter a buffer. Thirty minutes is the starting value in the box. Raise it if you want daylight to spare.
- Press Calculate. The hero is the latest turn. A negative margin means that start already misses sunset.
How it's calculated
One-way minutes = (distance ÷ 2) × pace. The planned turn, if you start on time, is start plus that one-way time. Back at camp is start plus twice that time.
Latest turn = sunset − one-way minutes − buffer. Margin = sunset − the time you would get back. The pace is assumed to be the same in both directions.
Worked example
Eight miles at 20 minutes per mile is 80 minutes each way. Start at 14:00 and the planned turn is 15:20, with a return at 16:40. Sunset at 18:30 and a 30-minute buffer put the latest turn at 16:40. The margin after the hike is 110 minutes. An earlier mental shortcut that called the latest turn 16:00 forgot that the buffer is subtracted from sunset along with the one-way time, and 18:30 minus 80 minutes minus 30 minutes is 16:40.
Assumptions
Same pace both ways, a sunset you looked up, and a buffer you chose. The page does not know the date or the trailhead. Type the sunset from a source you trust.
FAQ
How is this different from finish before dark?
Finish before dark takes a one-way plan and an elapsed time and compares the arrival to sunset. This page splits an out-and-back and names the latest turn.
What does a negative margin mean?
The start time plus the full hike already passes sunset, even before the buffer. Move the start earlier or shorten the route.
Should the pace be slower on the way back?
If you think so, type the slower pace. The form uses one pace for both halves.
Does the buffer include photos and breaks?
Only if you put those minutes in the buffer or slow the pace. The form does not add them.