Why the Way Down Takes Longer Than Naismith Says
Ask most hikers which half of a mountain day is harder and they will say the climb. Ask which half takes longer than they expected and many will say the descent. Going down uses less energy, but on steep, loose or rocky ground it is slow, careful work, it comes at the end of the day when legs are tired and light is fading, and it is where most slips and twisted ankles happen. Time estimates tend to underplay it. This guide looks at why, and at how the Daylight Turnaround Calculator's return-slowdown setting accounts for it.
What Naismith's rule says about descents
Naismith's rule, which the Hiking Time Calculator uses for its main estimate, charges one hour per 5 km of distance and one hour per 600 m of ascent. It charges nothing for descent. For a hypothetical out-and-back of 12 km with 800 m of climb, split into its two halves at average pace:
- Up: 6 km with 800 m of climb, 2h 32m.
- Down: 6 km with no ascent, 1h 12m, which is the rule's flat walking rate.
- Round trip: 3h 44m.
So by the rule, the descent takes less than half as long as the climb. On a smooth, gently graded path, that can be close to true; fit walkers on good paths do come down quickly. On a steep, rough path, it is often badly wrong. Coming down 800 m of steep, loose ground at flat-walking speed is something few people can do safely.
The rule's author knew this; Naismith's rule was always intended for reasonable paths, and later refinements, such as Langmuir's corrections used in Scottish mountain training, add time for steep descents and subtract a little for gentle ones. The calculator keeps the simple rule and leaves you to adjust for the ground.
Why descents are slow in practice
- Footing. On loose stones, wet rock, roots, mud or snow, every step down needs care. Going down, your weight lands on the foot you cannot fully see.
- Knees and legs. Descending loads the thigh muscles as they lengthen under tension, which is tiring in a different way from climbing. Tired legs shake, and shaky legs slip.
- Fatigue. The descent comes after the climb. You are slower, and attention wanders.
- Light. Late in the day, light fades, especially in forests and valleys, and the descent is when you meet it.
- Groups. A group descends at the pace of its most cautious member, and should.
- Load. A heavy pack makes balance harder going down than going up.
Energy is a different matter: descending costs much less than climbing, and the calorie estimate reflects that. See how the Pandolf equation handles descents. Time and energy do not move together on the way down.
How the turnaround calculator handles the way back
The turnaround calculator does not split your hike into climb and descent. It takes your round-trip estimate, treats the outward and return legs as halves, and then assumes the return takes longer than the outward leg by a percentage you set. The default is 25%. It is a planning allowance rather than a measured figure, and it is deliberately on the cautious side: the calculator never assumes you come back faster.
That slowdown changes the turnaround time. For the 12 km route, with 45 minutes of breaks added to the 3h 44m, a start at 08:00, sunset at 17:00 and the default 60-minute buffer:
| Return slower by | Turn back by | Projected finish | Margin |
|---|---|---|---|
| 0% | 12:00 | 12:29 | 211 min |
| 25% (default) | 11:33 | 13:03 | 177 min |
| 50% | 11:12 | 13:36 | 144 min |
| 75% | 10:54 | 14:10 | 110 min |
Each step makes the turnaround earlier, because more of the usable daylight is set aside for the way back. With no slowdown, the turnaround sits exactly halfway through the window, at 12:00; at 75% it moves more than an hour earlier, to 10:54. The projected finish moves later at the same time. Both changes point the same way: more caution about the descent means turning back sooner.
Choosing your slowdown
The best number is your own. After a few hikes, compare how long you took to go out with how long you took to come back on the same route. Many watches and apps record this. Some guidance in the meantime:
- Good, gently graded paths, fit walkers: the default 25% is generous, and that is fine. Spare time at the end of a day is never wasted.
- Steep, rough or loose descents: consider 50% or more, especially if the route description mentions scree, scrambling or exposed sections.
- Mixed groups, children, heavy packs, or anyone with knee problems: err higher.
- Winter, wet or icy conditions: err higher again.
If in doubt, choose the higher figure. The only cost is turning around a little earlier.
Logging your own descents
A few minutes of record-keeping turns the slowdown from a guess into a measured number. For each out-and-back hike, note:
- The time you left the trailhead and the time you turned around.
- The time you got back.
- Your stops on each leg, roughly.
- The kind of ground on the descent: smooth path, rocky, loose, wet, snowy.
Subtract the stops, then divide the return moving time by the outward moving time. If the outward leg took 2 hours of moving time and the return took 2 hours 30 minutes, your return was 25% slower, which happens to be the calculator's default. If it took 3 hours, you were 50% slower. After five or six hikes you will see a pattern, often a different one for smooth paths and rough ones, and you can use the right figure for the route ahead.
Loops and point-to-point routes are harder to compare this way, because the two halves are different ground. For those, note how your total time compared with the Hiking Time Calculator's estimate instead, and use the pace setting that fits.
Descending more safely
- Slow down deliberately on steep ground. Short steps, knees soft, weight over your feet.
- Use trekking poles if you have them; many people find they take load off the knees and help balance.
- Eat and drink before the descent. Low energy makes legs weaker and attention poorer.
- Put on the headlamp early if the light is going, not when you can no longer see the path.
- Stay on the route. Shortcuts down unknown slopes are a common way to get lost or stuck above a drop.
- Keep the group together, with the slowest walker setting the pace.
The plan, end to end
Estimate the round trip with the Hiking Time Calculator and add your breaks. Choose a return slowdown that fits the descent you will face. Put both into the turnaround calculator with your start and sunset times. Turn back when the time comes, even if the top is close; see how to set a turnaround time. Carry a headlamp, layers, food and water, first aid, a map and a charged phone. Tell someone your route and when you expect to be back, and know the local emergency number. Check the land manager's current conditions, which may tell you about the state of the descent path before you are standing at the top of it.