Hike Turnaround Time Calculator for National Park Trails

How it works

1. Sunset for the park and date comes from the same solar calculation as our sunrise and sunset tool, using the park's NPS reference coordinates and local time, including daylight saving time where it applies.
2. Back-by time is sunset, or the end of civil twilight if you choose it, minus your safety margin.
3. Hiking time is distance divided by your pace.
4. Latest turnaround for an out-and-back is the back-by time minus half the hiking time.
5. The headline is the earlier of the latest turnaround and your planned halfway point.

Worked example

Zion, November 14, 2026. Start at 1:00 p.m. for an 8-mile round trip at 2 mph with a 30-minute margin.

• Sunset: about 5:23 p.m. MST. Back-by: 4:53 p.m.
• Hiking time: 4 hours. Halfway at 3:00 p.m.
• Latest turnaround: 2:53 p.m. Finish at your pace: 5:00 p.m., seven minutes past the back-by time.

Options: start before 12:53 p.m., shorten the route, or turn around at 2:53 p.m.

Choosing a pace

Pace varies a lot between people and trails. The best input is your own measured pace on similar terrain:

• Time a familiar hike and divide distance by total time, including short breaks.
• Use a slower pace for steep, rocky or high-altitude trails, or in heat.
• If you're hiking with others, use the slowest person's pace.

Choosing a margin

A margin covers what you can't predict: a wrong turn, a slow climb, a sore ankle or a longer lunch. Thirty minutes is a reasonable starting point for many day hikes; increase it for long or unfamiliar routes, winter conditions or canyons. The calculator doesn't pick it for you.

Canyons and mountains get dark early

The calculator uses sunset for a level horizon. In a canyon or on the east side of a ridge, direct sunlight can disappear well before sunset, and it cools quickly. Treat the result as the latest safe plan, not a target.

Hot weather changes the plan

In summer, the problem is often heat, not darkness. Grand Canyon rangers advise avoiding hiking between 10 a.m. and 4 p.m. and finishing in the late afternoon or evening. A late-day finish makes your turnaround time even more important. See hiking in the heat.

Always carry

• A headlamp or flashlight and spare batteries; rangers say not to rely on a phone.
• More water and food than you expect to need.
• A map, and a plan someone at home knows about.

Common questions

What pace should I enter?

Your own. Time yourself over a known distance on similar terrain, including short breaks. The 2 mph in the form is only an example.

Why use the end of civil twilight?

The U.S. Naval Observatory defines it as when artificial light is normally needed for ordinary outdoor activities. It's the practical limit of usable light, but leaves no slack, so keep a margin.

Does it account for elevation gain?

No. Climbs slow most people, especially on the way up. If your hike climbs a lot in one direction, use a slower pace or a bigger margin.

Does it work for loops?

Use the expected finish and latest start figures. The turnaround time applies to out-and-back routes.