How to prepare for a day hike without misjudging the effort

The first hike I properly got wrong was eleven kilometres. Eleven kilometres, on paper, is a walk. Except there were nine hundred metres of climbing in it, I had never looked at that line, and I reached the col three hours later than the time I had given at home.

That is the mistake everyone makes at the start: preparing for a hike by looking at the distance. Here are the five things I look at now, in order.

1. Elevation gain before distance

In the mountains, distance tells you almost nothing. It is the total elevation gain, the number of metres you are going to climb, that sets the duration and the fatigue.

The rule that works: count 300 metres of climbing per hour for an average walker, and add flat distance at 4 kilometres per hour. Take the larger of the two, not the average. An outing of 11 km with 900 m of gain isn’t 2 h 45, it is three hours of climbing with the descent still to come.

The descent is the part everyone forgets. It takes roughly two thirds of the climbing time, and it is what wrecks your knees. A hike isn’t over at the summit, it is over at the car.

2. Your finish time, worked out backwards

Don’t start from a departure time. Start from sunset, subtract an hour of margin, and work backwards.

That calculation is what changes everything in autumn. In late October it is dark by six in the Pyrenees. A six hour round trip therefore has to start by eleven at the latest, breaks included, and eleven is already late for a high car park at the weekend.

3. Mountain weather, not town weather

The forecast shown for the valley is worth nothing a thousand metres above it. Three numbers to look for, in this order:

• The freezing level. That is the altitude at which it freezes. If it sits at 2,200 m and your col is at 2,400, there will be ice on the shaded sections early in the morning.
• The wind on the ridge, not at ground level. Fifty kilometres an hour in a col is unpleasant. Seventy on an arête is dangerous.
• The time storms are due. In summer they build in the afternoon. If the risk starts at two, you need to be off the ridge by two, not arriving on it.

4. What goes in the pack, and what doesn’t

After a few years my list got shorter rather than longer.

What is always in it: a litre and a half of water minimum, a windproof layer even in good weather, a head torch, twice as much food as I think I need, and the offline track on the phone. The head torch is the thing you never take and need once in thirty outings, on precisely the day you are running late.

What is no longer in it: the tripod, the second lens, the book. A spare kilo is paid for on every metre of climbing.

5. Tell someone, with the route

One sentence to somebody before you leave: where you are going, by which route, and what time you will be back. It is free, it takes ten seconds, and it is the only item on this list that really counts if things go wrong.

After the hike, the part nobody prepares

We prepare the before at length, and the after not at all. Six months later you no longer know whether that outing had 700 or 1,100 metres of climbing in it, or how long it actually took.

And yet that is the single most useful piece of information there is, because it is what lets you judge the next one properly. My real climbing rate isn’t 300 metres an hour, it is closer to 380 when I’m fit and 250 at the end of the season. I only learned that by accumulating recorded outings.

That is what pushed me to build Summit Journal, which records the track, the elevation and the real time of every outing, and turns it into a journal you go back to. It isn’t essential for preparing a hike. It is what makes the tenth one more accurate than the first.

The summary, if you only keep one thing

Look at the elevation, not the distance. Work out your timing from sunset rather than from the start. And tell somebody. The rest you learn by walking.