Hiking time and arrival calculator
How long a walk really takes, when you get back and how much daylight is left, with the arithmetic shown step by step.
Type the distance and the elevation you read in a route description or on a trail sign, pick your pace and get the walking hours, the time you are back and the margin left.
Distance here is the length of the path measured on the map. If you come back the same way, enter the outward leg only and tick the box above: the tool doubles the kilometres and adds the two elevation figures together, because on the way back the climb becomes the descent and the other way round.
The three numbers can be edited, and as soon as you change one the pace becomes custom. Once you have walked a route with this tool, the honest way to calibrate it is to work out your real climbing rate (metres climbed divided by the hours it took, breaks excluded) and type that here.
The cut off time is sunset, the last bus or the last cable car. Leave it empty and you only get the time you are back. For sunset on the right day and place there is the Sunrise and sunset tool.
Where walking hours come from
The method used on Italian trails does not simply add times up. You work out how long the elevation takes (300 metres per hour uphill and 500 downhill, for an average walker with a light pack), then how long the distance takes (4 km/h), and finally you take the larger of the two plus half of the smaller. Half of the smaller is not a random fudge: it avoids counting the same ground twice, because while you climb you are covering the kilometres as well. On a 12 km round trip with 900 metres of ascent and the same descent that gives 3 h 45 min up and 2 h 33 min down, so 6 h 18 min of pure walking. The calculation is done separately on the ascent and on the descent, splitting the kilometres between them in proportion to the elevation.
A hundred metres of ascent cost more than a kilometre of flat
With the standard figures 100 metres of climbing take 20 minutes, and in 20 minutes on the flat you cover 1.3 km. That is why two walks with the same distance can take twice as long as each other, and why the right question in front of a trail sign is not how long it is but how much it climbs. Downhill the ratio almost halves (100 metres cost 12 minutes), but only while the ground is good: on scree, mud or soft snow the descent can become slower than the climb, and that is when the rough ground box earns its place. The three condition percentages add up to each other and apply to all three methods, so the numbers stay comparable.
Naismith, Langmuir and Tobler, three ways of estimating the same thing
Naismith's rule dates from 1892 and comes from the Scottish mountaineer William W. Naismith: one hour per 3 miles (4.8 km) plus one hour per 2,000 feet (610 m) of ascent. It says nothing about the descent, and Eric Langmuir's correction adds it: 10 minutes less per 300 metres when the descent is gentle (between 5 and 12 degrees), 10 minutes more when it is steep (over 12 degrees). Tobler's function, from 1993, gives a speed rather than a time, 6 times e to the power of (-3.5 times the absolute value of slope plus 0.05) km/h, and it was born for computer models of the landscape. Its maximum is not on the flat but on a gentle 5 per cent descent, which really is the ground people walk fastest on. It describes a brisk pace on a good path, so it almost always returns the lowest figure; off path its author suggests multiplying the speed by 0.6. Seeing the three numbers side by side is the whole point of this page: when they are close the route is steady, when they are far apart it is either very steep or very long, and the safest choice is the most cautious one.
Breaks are not inside the walking hours
None of the three methods counts stops, and that is the first reason people get back later than planned. The proportion that holds in practice is 10 minutes per hour of walking, plus half an hour when lunch is involved: on a 6 hour day that is an extra hour and a half. This is why the result keeps walking hours and the length of the whole day apart, and uses the second one for the time you are back. The figure written on a trail sign is always the first of the two, never the second.
What the calculation cannot know
This is an estimate, not a guarantee. Heat, headwind, altitude (above 2,500 metres an unacclimatised walker slows by 10 or 20 per cent), the tiredness that builds up during the afternoon, snow that holds at eight in the morning and collapses at noon, and above all the sections where time depends on technique rather than pace, such as a via ferrata, a gully, a river crossing or an exposed ridge: there no formula means anything and only the account of someone who has been there counts. The input itself is approximate too, because the distance read on a map is the flat projection, while a GPS track measures a few per cent more. Before you set off check sunset for the right day and place, tell somebody where you are going and carry a head torch even when the numbers add up.