Hike Time Calculator & Turnaround Planner

Hiking turnaround time and call-for-help time: how to plan them

A turnaround time is the clock time at which you start heading back, whatever progress you have made. Work it out backwards: pick the time you must be back (for example 30 minutes before sunset), subtract the time the return leg needs including breaks, and you have the latest moment to leave the far point. A call-for-help time is the time you tell someone to raise the alarm if they have not heard from you. Both are set before you leave, when your judgment is clear, so that you do not have to negotiate with yourself when you are tired and the summit is near. The hike time calculator works out both.

Why turnaround times matter

Many hill rescues begin with a walker who is neither lost nor injured, only late. Darkness arrives sooner than expected, the descent is slower than the ascent, and the group is tired. A turnaround time converts a vague intention ("we will turn round if it gets late") into a rule that is easy to follow: when the watch says 14:15, we turn. The rule works because it removes a decision at the moment when summit fever and the sunk-cost feeling are strongest.

Step 1: find out when it gets dark

Sunset is not the end of usable light. Civil dusk, when the sun is 6 degrees below the horizon, is the point at which you can no longer read a map or follow a path without artificial light. At mid latitudes civil dusk comes roughly 30 to 50 minutes after sunset, and closer to the poles, especially in summer, the gap is much longer. In a valley or under tree cover, the sun disappears behind terrain much earlier than the official time, so real light may fade 30 to 60 minutes before sunset. The calculator shows sunrise, sunset and civil dusk for your date and location, so you can see the gap.

If you carry a headlamp with spare batteries and know the route, you can plan to finish after dark. If you do not, plan to finish at least 30 minutes before sunset, and in rugged or wooded terrain more than that. This is what the "safety buffer before sunset" setting is for.

Step 2: estimate the return leg honestly

The return leg is not always the mirror of the way out. Time depends on gradient: a long climb on the way out turns into a long descent on the way back, which the Langmuir correction treats as faster if it is gentle and slower if it is steep. The calculator swaps ascent and descent on the way back for out-and-back walks. Most people also walk more slowly late in the day, so add margin if the return is on tired legs or on rough ground, and use the slower of the three methods.

As an example, take a 7 km walk with 600 m of ascent out and back. With the Naismith plus Langmuir method and a day pack, the way back takes about 2 hours 4 minutes of walking, or about 2 hours 25 minutes with rests at 10 minutes per hour. If you need to be back at the car by 18:00, you must leave the top at 15:35 at the latest. A fixed 30 minute stop at the top means arriving by 15:05. If you are still climbing at that time, turn around.

Step 3: set the "back by" time and the latest start

Subtract the buffer from sunset to get the "back by" time, then subtract the whole trip length to get the latest start. If sunset is at 17:50, your buffer is 30 minutes and the trip takes 5 hours 30 minutes, the latest start is 11:50. Setting off at 13:00 means you are planning to finish in the dark. Rather than hoping to move faster, choose a shorter route, which the calculator lets you test by changing the distance and ascent.

Step 4: decide on a call-for-help time

A call-for-help time is for the person who is expecting you. Give them your route, your start time, your expected return time, and a time after which they should contact the emergency services if they have not heard from you. It should be later than your expected return, so people are not alarmed by a short delay, but early enough that rescuers have time to find you. The calculator suggests the later of your planned finish and your back-by time, plus a margin of 60 minutes. Adjust the margin to match your own situation: a short low-level walk might justify a shorter margin, a remote day in winter a longer one together with a firm plan to check in by phone or satellite messenger.

The calculator produces a plain text plan that you can copy and send. It contains the date, the route figures, the expected finish, the turnaround time, the back-by time and the call-for-help time. Add the name of the trailhead, your car's registration number and the intended route and escape options, which are the details that matter most to a rescue team.

What a calculator cannot do

This website does not monitor you or contact anyone. It cannot raise an alarm if you are late, because it has no connection to you once you close the page. If you are hiking alone and want an automatic alert, use a method that works without the page: a trusted person who knows your call-for-help time, an emergency-location app that your local emergency service supports, a satellite messenger or a personal locator beacon in places with no phone signal. Phone batteries run down in the cold, so carry a spare power bank, keep the phone warm, and carry a paper map and compass as well as a phone map.

The numbers on screen are estimates. Weather can slow you down, make navigation harder or change the plan altogether. Check the forecast before you go and be willing to cancel, shorten or turn around early. Experienced walkers also write down a second, earlier turnaround time based on weather or on the group's speed: if the first checkpoint is reached more than 30 minutes behind schedule, they turn at once.

A simple checklist

To see how the time estimate itself is built, read Naismith, Langmuir and Tobler explained, then return to the calculator to plan your next walk.