How to choose a backpacking kit: the big four, in the right order

Most kit advice starts with the four categories and works down through features. That is the wrong end. Start instead with the nights you will actually spend outside: how many of them in a row, in which months, on what ground, and how far from a road. Every specification that follows answers one of those.

Be honest about the trips you already make rather than the ones on the list. For most people the real pattern is one or two nights between April and October, on ground far more often wet than frozen. Kit built for that is lighter, cheaper and more pleasant to carry than kit built for a January bivouac that has not been booked. If the expedition happens, a second sleeping bag is a nicer problem than a first kit you resent.

Those are the questions the finder asks, in that order: the lowest night temperature, the number of nights, the ground, the weather, and how many of you there are. Then it asks about you, because the same night is a different night for someone who sleeps cold.

The first answer becomes a temperature: the lowest air temperature you expect overnight, where you are going, in the month you are going. Not the daytime high, and not the regional average. Cold air sinks and settles, so a clear, still night in a hollow or a valley floor runs colder than the forecast for the nearest town, and altitude takes more off again.

That single number does two jobs, not one. It sets the sleeping bag, and it sets the sleeping pad. The two figures come from different standards, measure different things, and neither can cover for the other.

Two cautions about that table. The comfort rating is an ISO 23537 figure produced on a heated manikin in a laboratory, lying on a mat, wearing a defined set of base layers. It describes a standard sleeper under test conditions, not your metabolism on a windy col. The R-value is measured under ASTM F3340, the standard that finally made pads comparable between brands. The long versions are in sleeping bag temperature ratings and sleeping pad R-values .

For scale: across the 87 bags here the comfort ratings run from +15 °C to −28 °C, with a median of −4 °C. Across the 63 pads the R-values run from 0.5 to 8.5, with a median of 3.4. The middle of both pools is a three-season kit, which is what most people are shopping for whatever they tell themselves at the counter.

The reason the order matters is that two of the four do one job between them. A sleeping bag insulates by loft: air trapped and held still by down or by fibre. Underneath your body that loft is crushed flat, and flat insulation insulates almost nothing. So everything between you and the ground comes from the pad — and the ground pulls heat out of you far faster than still air does, because contact with a solid conducts where air only convects.

That is why a warm bag on a thin mat is a cold night, and why a modest bag on a good mat often is not. Buy the two as one decision. If the money runs out partway, let it run out in the bag rather than in the pad.

The tent is a different question. It does not keep you warm in any meaningful sense; it keeps the weather off you, which is a separate and sometimes larger problem. Wind, driven rain and condensation ruin nights that were warm enough on paper. Flysheet hydrostatic heads here run from 1,200 mm to 5,000 mm, and the shapes split into 36 tunnel, 30 dome and 17 semi-freestanding — decisions about ground, pitch and wind rather than about temperature. Choosing a tent works through them.

And the pack has no job of its own. It carries the other three, plus your food, water and clothes. Its size, its frame and its price are all consequences of decisions you have not made yet. That is the entire argument for buying it last, and it is the argument almost everyone ignores.

1. 1

   The pad

   Set the R-value from the coldest night, then choose the type. There are 46 air pads, 9 self-inflating and 8 closed-cell foam mats here, from €30 to €280 with a median of €130. It is the cheapest of the four slots and the one people cut first, which is exactly backwards. If you sleep on your side, thickness matters as much as R-value: the pool runs to 10 cm inflated, and a hip on a thin mat finds the ground.

2. 2

   The bag

   Now choose the bag knowing what is underneath it. Match the comfort rating to the same night, then decide between down and synthetic on how wet the trip is and how long the bag has to stay dry. Check packed volume as well as weight: bags here run from 2.5 to 24 litres packed, nearly a tenfold difference in how much of the pack they eat. Check length too, because a bag you cannot stretch out in is a bag you fight all night.

3. 3

   The tent

   Choose for the ground and the weather, not for the temperature. Whether it is freestanding decides whether you can pitch on rock, gravel or a wooden platform; the number of doors decides whether two people climb over each other at three in the morning; the season rating decides whether it will stand up under snow. Packed weight runs 540 g to 4,200 g here with a median of 1,740 g, and that span is most of the difference between a light kit and a heavy one.

4. 4

   The pack

   Only now do you know what the pack has to hold. Add the packed volumes of the other three: at catalogue medians that is 7 litres of tent, 6.5 of bag and 3.5 of pad, so 17 litres before any food, water or clothing goes in. Add those, then buy for the total rather than for the trip in your head. Sizing a pack is a separate job from choosing one, because packs are sized by torso length rather than height.

The order is not a ritual. Each step removes options from the next: the pad sets how warm the bag must be, the bag and tent set the volume, and the volume sets the pack. Run it backwards and every step is a guess.

Price buys different things in each slot, and only one of the four is buying safety at the margin.

The cheapest item in each pool gives a kit of €255. The median of each gives €1,220. The dearest of each gives €3,180. The interesting changes are almost all in the bottom half of that range; the top half mostly buys grams. How much to spend takes the split apart, including why an even four-way one is wrong.

Buying the pack first

It is the most visible item, the one with a brand on the front, and the one shop staff will fit for you. It is also the one whose requirements do not exist until the other three are chosen. Buy 65 litres before you own a tent and you will fill 65 litres; buy 40 and find your tent packs to 13 litres and you will be strapping things to the outside for the rest of its life.

Buying for the coldest night you can imagine

A bag rated well below your real conditions is heavier, bulkier, more expensive and, on an ordinary night, too hot to sleep in — so you vent it and sleep badly anyway. The pools here reach −28 °C and R-value 8.5, and almost nobody needs either. Choose for the coldest night you will realistically have, and handle the occasional colder one the way experienced walkers do: a warmer base layer, a hat, a hot drink, a liner.

Treating a temperature rating as a promise

It is a laboratory result, not a guarantee, and it assumes a pad underneath, clothing on, and a sleeper who is fed, dry and not exhausted. Wind, damp down, a missed meal or a long day all move the real figure the wrong way. Keep a margin, particularly if you sleep cold or the trip is remote. Hypothermia does not arrive dramatically; it arrives as a bad night that gets worse, and the way to avoid it is a system with room in it rather than a number on a label.

Four decisions, in order, from one honest description of a trip. That is the method. If you would rather see the output before doing the work, these are complete kits assembled for particular trips, with the reasoning attached to each piece. None will be exactly your trip; they are here to show which piece moves when one answer changes.