The formula that started it all
In 1892, a Scottish mountaineer named William Naismith proposed a simple rule: allow one hour for every 5 kilometers of horizontal distance, plus one hour for every 600 meters of ascent. It is over 130 years old and still the backbone of most hiking time estimates.
For a 10-kilometer hike with 600 meters of climbing, that gives two hours for distance plus one hour for elevation — three hours total. In practice, most people need a bit more than that.
Adjusting for real conditions
Naismith assumed a fit walker on a good path. Add time for terrain, load and group pace. A rough trail with roots and rocks can slow you by 20 to 30 percent compared with a smooth gravel path.
- Add 10 to 20 percent for a heavy pack
- Add 20 to 30 percent for rough or steep terrain
- Add 30 percent or more for snow, mud or dense brush
- Add the slowest person’s pace, not the average
- Add 5 to 10 minutes of rest for every hour of walking
A worked example
Take a typical local loop: 12 kilometers with 800 meters of gain. Naismith gives 2.4 hours for distance and 1.33 hours for elevation, so about 3.7 hours. Add 25 percent for a rocky trail and a daypack, and it becomes 4.6 hours. Add four rest stops of 10 minutes, and the plan is about 5.3 hours.
A sensible plan is 5.5 hours, with any time saved treated as a bonus. That buffer is what keeps a hike from turning into a walk back in the dark.
Why the descent matters too
Naismith does not account for downhill. Descending is faster in terms of aerobic effort but harder on your knees, and steep descents can be slower than the climb. For a big elevation day, add 10 to 15 percent to the total for descent fatigue.
If the route has loose scree or wet roots, budget more. A fall on the way down ends more hikes than exhaustion on the way up.
Turnaround time beats total time
The most useful number is not your estimated total. It is your turnaround time — the clock time at which you turn around no matter where you are. Pick it before you start, write it on your hand, and stick to it. Light is the constraint that matters, and it does not negotiate.
