The most important factor that will determine the right size bug out bag is your torso size. You can measure your torso by having a friend or casual acquaintance measure the distance from the top of your Iliac Crest (hip bones) up to the bony prominence at the base of your neck (the last cervical vertebrae). Knowing the length of your torso will help you choose a bug out bag that fits comfortably.
A “Bug out bag” (sometimes called a “bail out bag” or “survival bag”) is loosely defined as a backpack-style bag that a person keeps at the ready in case they need to evacuate in a hurry (bug out) due to natural disaster, civil unrest, fire, war or any other similar type of calamity. A bug out bag won’t be much good should a comet the size of Dallas hit the earth but for the type of events listed above it can make the difference between thriving and barely surviving.
A while ago I wrote an article called 50 Items You Forgot To Put In Your Bug Out Bag. Several readers complained, saying things like, “How the hell am I supposed to fit all this stuff in my bug out bag?” Well, you’re not. The point of the article is to tell people about any items they would have included but either forgot about or hadn’t considered yet.
The whole point of a bug out bag is that it is ALWAYS packed and ready to go. In a true emergency, you might not have the time to throw those last few items into your bug out bag that you’ll really need. So, the short answer to this question is that the bag should be packed and ready to go at all times. But you should also be careful to regularly check any items in your bag that could expire or need replacement if they’ve been sitting for a while.