Quick answer: Put it inside if you can. REI places the sleeping bag in the bottom zone of the pack, often in a dedicated compartment, where it cushions your back and stays dry. If the bag will not fit, strap it under the pack using the bottom lash straps, inside a waterproof stuff sack, and keep it tight so it does not swing.
Bags strapped outside get wet, snag on brush and swing with every step. That is why modern packs have a bottom compartment.
This guide covers the inside method first and the outside method when there is no choice.
Related: tent camping gear checklist, packing zones and attaching a tent.
Inside the Pack
- Stuff the bag into its stuff sack, or directly into the bottom compartment to fill the space.
- Place it at the bottom; REI puts sleep gear there with the pad and camp shoes.
- Pack dense items above it in the core.
REI notes the sleeping bag compartment lets you reach the bag without unloading the rest.
Outside, If You Must
| Step | Why |
|---|---|
| Use a waterproof stuff sack | REI lists waterproof stuff sacks as an alternative to a raincover |
| Use the bottom lash straps or compression straps | REI lists lash-on points and compression straps for outside gear |
| Keep it tight and centered | Swinging weight throws off balance |
| Check it at breaks | Straps loosen on the trail |
If It Never Fits
A bag that never fits inside suggests the pack is too small for the trip. REI suggests 30 to 50 liters for weekend trips and more for multiday or winter, where bags are bulkier.
Honest Limits
Pack designs differ, and some have no bottom straps. We have not tested specific packs or bags.
Frequently Asked Questions
Should a sleeping bag go inside or outside the pack?
Inside, at the bottom, per REI.
Where exactly inside?
The bottom zone or sleeping bag compartment.
How do I strap it outside?
Bottom lash or compression straps, in a waterproof sack, tight and centered.
Will it get wet outside?
It can. Use a waterproof stuff sack.
Can I hang it on top?
Top is for trail essentials; a bag there makes the pack tippy.
Why does my pack swing?
Loose outside gear. Tighten it.
What if my bag is too big?
Compress it, or the pack may be too small for the trip.
Do I need a compression sack?
It helps the bag fit inside.
Can I attach a pad the same way?
Yes, REI lists a large pad among outside items.
Does outside gear snag?
Yes. REI advises limiting it.
Bottom Line
Pack the bag inside at the bottom whenever it fits.
Outside, use a waterproof sack and tight bottom straps.
Sources: REI, How to Pack a Backpack; REI, How to Choose a Backpack.