A bug-out bag is built around one job: keep you alive and mobile for 72 hours if you have to leave immediately. Everything in it should earn its weight against that job.
Core categories:
- Water (a liter minimum plus a filter or purification method — you can't carry 3 days of water, so plan to treat more en route)
- Food (calorie-dense, no-cook: bars, freeze-dried meals)
- Shelter (compact tarp or bivy, emergency blanket)
- First aid kit (see "Building a Basic First Aid Kit")
- Fire-starting (redundant methods — lighter plus ferro rod, not just one)
- Light (headlamp, spare batteries)
- Documents (copies of ID, insurance, emergency contacts, in a waterproof bag)
- Cash in small bills (card networks and ATMs may be down)
- Season-appropriate clothing layer
Common mistakes: packing for comfort instead of function, never actually weighing the bag (aim for roughly 10-20% of body weight for sustained carrying), and packing it once and never checking it again — batteries die, food expires, kids outgrow the spare clothes you packed for them.
Build it, weigh it, carry it around the block once. You'll immediately find what you overpacked.