Hike time calculator: how long will the walk take, and when must I turn back?
Enter the distance, total ascent and total descent: the calculator returns your walking time with breaks, a finish time for your start time, and, for out-and-back walks, the clock time at which you must turn around to be off the hill before dark. It runs three well-known methods side by side (Naismith, Naismith with Langmuir's descent correction, and Tobler's hiking function) so you can see how much they disagree, and it calculates sunset for your location and date.
How the calculator works
Naismith's rule allows one hour per 5 km plus one hour per 600 m climbed. Langmuir's correction then takes 10 minutes off for every 300 m of descent on gentle slopes (5 to 12 degrees) and adds 10 minutes for every 300 m on steep ground (over 12 degrees). Tobler's hiking function gives a speed from the slope, v = 6 e-3.5 |slope + 0.05| km/h, so about 5 km/h on the flat, 6 km/h on a gentle descent of 5 percent, and 3.5 km/h on a 10 percent climb. Because you enter totals, not a profile, the Tobler figure assumes your climbing and descending happen on slopes of the typical gradient you set, with the rest of the route flat.
The terrain, pace and pack settings multiply the moving time. Rests are added as minutes per hour walked, and fixed stops are added once. Sunset uses the NOAA solar position equations and is normally accurate to within a minute or two away from the poles. It ignores mountains and trees that hide the sun earlier than the horizon, so real light can fade sooner in a valley.
Worked examples
| Route | Naismith | + Langmuir | Tobler |
|---|---|---|---|
| 12 km loop, 800 m up and down (moving time) | 3 h 44 | 3 h 17 | 3 h 14 |
| 8 km one way, 700 m up, no descent (moving time) | 2 h 46 | 2 h 46 | 2 h 10 |
| 7 km out and back, 600 m up and down (moving time, both legs) | 4 h 48 | 4 h 08 | 4 h 19 |
The methods differ by up to 40 minutes on the same route, which is why the calculator shows the spread and suggests planning with the slower figure. To understand where each number comes from, read Naismith, Langmuir and Tobler explained. To turn a time estimate into a safe plan, read how to set a turnaround time and a call-for-help time.
Frequently asked questions
- How long does it take to hike 10 km?
- On flat, good ground a typical walker covers 10 km in about two hours of walking. Add one hour for every 600 metres of climbing (Naismith's rule), so 10 km with 600 m of ascent is about three hours of moving time before any breaks. Enter your own distance and ascent in the calculator to get the figure with breaks and a clock time.
- What is Naismith's rule?
- Naismith's rule is a rule of thumb for walking time: allow one hour for every 5 kilometres (3 miles) on the map, plus one extra hour for every 600 metres (about 2,000 feet) of ascent. It was devised in 1892 and is still the standard starting point for planning a walk.
- What is the difference between Naismith, Langmuir and Tobler?
- Naismith counts distance and ascent only. Langmuir's correction adjusts Naismith for descents: gentle descents save time, steep ones cost time. Tobler's hiking function is a formula that gives walking speed from the slope, so it handles every gradient. The calculator shows all three side by side.
- How do I work out the latest time to turn around?
- Decide when you must be back (for example 30 minutes before sunset), then subtract the time the return leg needs, including breaks. For an out-and-back walk the calculator does this for you and shows a turnaround clock time. Turn around at that time even if the summit is close.
- How accurate is the estimate?
- Treat it as a planning figure that is typically within 15 to 25 percent for ordinary trails. Fitness, pack weight, weather, navigation and terrain all matter. After a few walks, compare the estimate with your real times and set the pace setting to match.
- Does the calculator send my location anywhere?
- No. Everything, including the sunset calculation, runs in your browser. If you press 'Use my location' your browser asks permission and the coordinates are only used to calculate sunset on this page. Nothing is uploaded or stored.
This calculator is a planning aid, not a substitute for navigation skills, weather forecasts or local knowledge. Conditions change; decide on the hill, not on the screen.