Guide 4 min
What backpack volume for a day hike, a wild camp, a trek?
20, 45 or 60 litres? Volume doesn't come from how many days you're out, but from what you put in. The ranges, the coefficients, and the calculation.
The backpack is the one purchase you can't fix once you're out there. Too small and it won't close, and the sleeping mat ends up strapped to the outside. Too big and you fill it, it always happens, and you carry two kilos you never needed.
The short answer fits in three lines. The rest of this page explains where they come from, and how to check that yours holds up.
The three ranges
| Trip type | Volume |
|---|---|
| Day hike | 15 to 25 L |
| Wild camp, one or two nights | 40 to 50 L |
| Trek, three nights or more | 50 to 65 L |
These are the ranges WildKit uses to suggest a bag. They don't come from a market average. They bracket what the rest of your kit actually takes up once it's folded away.
Volume comes from your sleeping bag, not from how long you're out
Two nights or four, your sleeping bag takes up the same space. It's the sleeping bag, the tent and the sleeping mat that set the volume. Food goes on top.
Here's what one kilo takes up once packed, item by item:
| Item | Litres per kilo |
|---|---|
| Sleeping bag | 8 |
| Sleeping mat | 6 |
| Down jacket | 5 |
| Tent | 4.5 |
| Fleece | 4.5 |
| Rain jacket | 3.5 |
| Breathable top | 3.5 |
| Trousers | 3 |
| Cookpot | 3 |
| Everything else, by default | 2.5 |
This table reads both ways. The sleeping bag is the bulkiest thing per kilo. Each kilo costs 8 litres, nearly double what a tent costs at 4.5. That's why a compressible sleeping bag changes the size of your backpack, while a lighter stove doesn't change the volume at all.
Weigh your sleeping bag and multiply by 8. That's its volume in litres. Do the same with the sleeping mat and the tent. You already have half the answer.
Heavy, but not bulky
Three items are on you while you walk, not in the bag. So the first one of each doesn't count towards the volume:
- the breathable top you're wearing;
- your trousers;
- the first pair of socks.
Footwear never counts towards the volume. It's on your feet. It does weigh, though.
Get this backwards and it costs you: the down jacket, the fleece, the rain jacket and the beanie do count. While you're walking they're in the bag. That's what the bag is for. Treating them as worn clothing wiped about 1.7 kg off the weight total, which your list was still showing line by line.
Food and water take up the space you forget
Allow 0.7 kg of food per person per day, plus 10% in winter. For a day trip, 0.3 kg of snacks is enough.
Three days for two people comes to 4.2 kg of food. It shows in the bag, and it's the line gear lists most often forget to count towards the volume.
The water you carry counts as 1.5 litres per person, and 2 litres once it's 22 °C or above.
When the range gives way
If nothing in the range for your trip type holds your kit, WildKit widens the range upwards instead of making you cram everything in. A backpack that's a bit too big beats a backpack that won't close. It happens fast. With four people on a wild camp, the gear goes past 70 litres, and no backpack in the 40-50 range works any more.
Two messages come out of that, and they don't say the same thing:
- Your bag is too small is an error. A bigger one exists in the range, and your gear doesn't fit the one you picked.
- Your bag is outside the range is a warning. It holds your kit, but it sits outside what we expect for this trip type.
What to remember
- Day hike 15 to 25 L, wild camp 40 to 50 L, trek 50 to 65 L. Start there.
- Weigh your sleeping bag, your sleeping mat and your tent, apply the coefficients. You'll know whether your range holds.
- What you wear doesn't fill the bag. Your down jacket does.
The full calculation, your sleeping bag, your tent, the weather for your trip and the number of people, happens automatically: we do it for you. Describe your trip, and compare the capacity we suggest with the estimated volume right next to it.
A guide WildKit keeps up to date. Published .