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For overnight camping, buy the backpack after you have gathered the bulky equipment. Your tent, sleeping bag and mat determine far more than the number of nights printed on the itinerary. One night with a large synthetic sleeping bag can need more room than several nights with a compact setup.
Table of Contents
Build the load before choosing litres
Group the equipment into shelter, sleep, clothing, food, water and small essentials. Include tent poles and pegs, rather than measuring the flysheet alone. If you share equipment, agree who carries each component before trying bags: carrying the cooking kit and food may offset a partner taking the tent.
Use the equipment’s packed shape as well as its stated volume. A long pole bundle can be awkward inside a short rucksack, while a broad sleeping mat may block access to everything beneath it. Do a real packing trial wherever possible.
Choose a useful trial range
For a first comparison, try packs around 40–60 litres with the complete overnight load. This is an editorial starting range, not a requirement. Compact summer equipment may fit into less; bulky bedding, extra layers or shared equipment may need more. Do not leave weather protection or other essential kit behind to meet a target number.
The pack should close properly without its lid floating over a mound of unsecured equipment. Leave enough room to put the kit back after use, when careful factory-style rolling is less likely. A wet tent may also need to travel separately from your dry sleeping equipment.
Keep the sleeping kit protected
Use an internal packing system that keeps dry clothes and bedding away from a wet shelter. A Sea to Summit Lightweight Dry Bag in the 20-litre size is one product to compare after checking your equipment fits. It is a storage option, not a guarantee that every sleeping bag will fit that size.
The manufacturer advises against submersion. A roll-top bag should therefore not be treated as an underwater case for valuables. Inspect the closure and leave space to close it as instructed.
Test the weight, not just the space
Lift the loaded rucksack and put it on carefully. Check the manufacturer’s recommended load range and fitting instructions, then walk long enough to notice movement or pressure. A large pack can hold a load that you do not want to carry; unused litres do not create permission to pack another heavy comfort item.
Before leaving, practise retrieving your waterproof jacket without emptying the bag. Keep the things needed at the first stop accessible, while putting bedtime-only equipment deeper inside. Check that nothing hard presses through the back panel.
What if your existing bag is nearly big enough?
Repack once before replacing it. Remove duplicate containers, divide shared equipment sensibly and loosen overly rigid bundles where the equipment allows. Avoid solving the problem by dangling multiple loose bags from the outside: they can snag, swing and complicate transport. If the complete load still prevents a proper closure, choose a more suitable pack or revise the equipment itself.
For extra meals and supplies, compare the three-day backpack sizing guide. Keep that capacity trial separate from the torso-length fit check.
Continue with our backpack packing guide.
Reviewed 10 September 2026. This guide is based on published specifications and guidance.