Compact CampingBackpack sizing: torso length and litres
Backpack size is two separate things: torso length, which decides whether the pack fits your back, and capacity in litres, which decides what fits inside. Get torso length right first - it is the one you cannot fix later.
Torso length is not height
Two people of identical height can need different pack sizes, because packs fit the distance from the C7 vertebra — the bony bump at the base of your bent neck — down to the top of the iliac crest, the shelf of your hip bones. Have someone run a tape between those two points along your spine: roughly 40–45 cm is a typical "small/medium", 45–50 cm "medium/large", but every brand cuts differently, so use their chart with your number.
The hip belt does the carrying
A fitted pack rests 70–80% of its weight on your hips, not your shoulders — hips route load into your legs, shoulders route it into your spine. The belt should wrap the top of the hip bones snugly, with shoulder straps merely hugging, not hauling. If the belt sits at your waist or the straps dig in, the torso length is wrong, and no amount of strap-pulling fixes a wrong-size frame.
How many litres does a backpack actually need to be?
| Trip | Compact kit |
|---|---|
| Overnighter, mild weather | 35–45 L |
| Weekend, three-season | 45–55 L |
| A week, or bulky shoulder-season gear | 55–65 L |
These assume genuinely compact gear — a small tent, a compressible down sleep system, a nesting cook kit. Traditional bulky gear adds 10–15 L to every row.
Buy the pack last
The pack should be sized to the kit, not the kit to the pack: a too-big pack gets filled, and a filled big pack is heavy. Assemble the rest of your gear first (the setup guide walks the order), pile it, and buy the pack that swallows the pile plus food with a hand's width to spare. Cutting base weight shrinks the litre number too.
Dial in the fit
Loading order matters: heavy items close to your spine at shoulder-blade height. Then, standing: hip belt first, snug on the bones; shoulder straps until they wrap without pressing; load lifters (the small straps at the top of the shoulders) tensioned to roughly 45 degrees. The pack should feel like it leans into you, not hangs off you.
Test with weight
An empty pack in a shop tells you nothing. Load 8–10 kg in — good shops have sandbags, or bring your gear — and walk stairs for ten minutes. Pressure points that appear at minute eight are the ones that ruin day three. Our compact backpacks picks carry honest litre and weight figures to start from.