How to Choose a Bug Out Bag Backpack: Size, Fit and Weight
Updated: 2 days ago
If you ever have to leave home fast, the bag on your back does a lot of the work. Most bug out bag advice is about what goes inside. This guide is about the bag itself. A bad pack can sink a good kit. It rips at the seams, soaks through in the first rain, or hurts your shoulders so much that you drop it after a mile. Here is how to choose a bug out bag backpack that fits your body, holds what you really need, survives bad weather and doesn't wear you out.
What a Bug Out Bag Backpack Needs to Do
A bug out bag is the kit you grab when you have to evacuate: a wildfire, a flood, a chemical spill, or an order to leave your neighborhood. The American Red Cross recommends a 3-day supply of water and food for evacuation and a 2-week supply for home. That 3-day number is why many preppers call it a "72-hour bag."
Not every government uses the same number. See how many days of emergency supplies governments recommend.
So the pack has four jobs:
Carry about three days of essentials for one person, without a pile of extras strapped to the outside.
Fit your body well enough that you can walk with it for hours if roads are jammed or closed.
Keep your gear dry and organized, so you can find a flashlight or first aid kit in the dark.
Hold up to abuse: being thrown in a trunk, dragged across a parking lot, rained on and overloaded.
Ready.gov's Build a Kit page notes that you won't know where you'll be when an emergency hits, so it suggests keeping supplies at home, at work and in your car. One good pack by the door, plus a smaller bag in the car, covers most people.
Step 1: Pick the Right Size (Capacity)
Backpack capacity is measured in liters. Bigger isn't better. An oversized pack invites you to fill it, and a heavy pack slows you down.
Rough capacity guide
These are general ranges, not hard rules:
20 to 30 liters: a get-home bag or car bag. It holds water, a light, a rain layer, snacks, a first aid kit and a few tools. It's good for getting from work to home.
35 to 50 liters: the sweet spot for most 72-hour bug out bags. It has room for three days of food, a water treatment method, a change of clothes, shelter items and a basic kitchen.
55 liters and up: this makes sense if you carry gear for a child, live somewhere very cold, or need bulky insulation. Be honest with yourself about whether you can carry it.
The Rothco 45L Tactical Backpack sits right in that middle range. It's built for multi-day loads, with multiple compartments for food, water, clothing and gear. If you want a classic three-day pack with MOLLE webbing, the Rothco MOLLE II 3-Day Assault Pack is sized for 72-hour or multi-day kits, with several compartments and MOLLE webbing to add pouches.
Size to your kit, not the other way around
Lay out everything you plan to carry on the floor first. Then pick a pack that holds it with a little room to spare. If your kit only fills half of a big pack, the load will shift and sag, and you'll be tempted to stuff it with things you don't need.
Step 2: Respect the Weight Limit
Weight is the part most people get wrong. REI's pack weight guidance for backpacking says a loaded pack should not weigh more than about 20 percent of your body weight. For a 150-pound person, that's about 30 pounds. For a day hike, REI suggests about 10 percent. REI says these are very general guidelines, not exact limits.
Water is the heavy part
Water weighs about 8.34 pounds per gallon, according to the U.S. Geological Survey. The standard guideline of one gallon per person per day means three days of water weighs about 25 pounds before you pack anything else. For most people, that's close to the whole weight budget.
That's why most bug out bags carry a smaller amount of water plus a way to make more:
Carry 1 to 2 liters in bottles, canteens or a hydration bladder.
Pack a filter or purification tablets to treat water you find along the way.
Keep the full gallon-per-day supply at home and in the car, where weight doesn't matter as much.
Our guide on how to find the best water filter for emergencies covers which filters and tablets make sense for a go-bag.
Do a real carry test
Load the pack with your actual kit, then put it on and walk around your neighborhood for 30 to 60 minutes. Take a hill if you have one. Pay attention to hot spots on your shoulders and hips, and anything that rattles, digs in or swings. A pack that feels fine in the living room can feel very different after two miles.
Step 3: Get the Fit Right
A pack that fits well feels lighter than a lighter pack that fits badly. Two numbers matter most: your torso length and your hip size.
Measure your torso, not your height
REI's fit guide explains how to measure torso length with a friend and a soft tape measure:
Tilt your head forward and find the bony bump at the base of your neck. That's your C7 vertebra, the top of your torso.
Put your hands on the top of your hip bones (the iliac crest) with your thumbs pointing back. Imagine a line between your thumbs.
Stand up straight. Your friend measures from C7 down to that line. That's your torso length.
Torso ranges differ between brands and models, so check the size chart for any pack you're considering. Two people of the same height can have very different torso lengths.
Let your hips carry the load
REI's backpack buying guide says most of a backpack's weight, 80 percent or more, should be supported by your hips. That's why a padded hipbelt matters on any pack you plan to carry for more than a short walk. Here's the basic adjustment order from REI's fit guide:
Hipbelt first: center the padding on top of your hip bones and buckle it snug, but not pinching.
Shoulder straps next: pull them down and back so they hug your shoulders, without carrying most of the weight.
Then the load lifters and sternum strap, if your pack has them, to pull the load close to your back and keep it from swaying.
If a pack has no hipbelt or only thin webbing, keep the load light and use it for short distances, like a car bag.
Step 4: Choose Materials That Survive Bad Days
Emergencies rarely come with good weather. Look closely at what the pack is made of and how it's put together.
Fabric and stitching
Tactical and military-style packs usually use heavy nylon or polyester fabrics and reinforced stitching at stress points like strap anchors and the haul loop. Canvas packs are tough and quiet but heavier, and they soak up water unless they're treated. Check the seams where the shoulder straps meet the body. That's where cheap packs fail first.
Zippers and buckles
Big, smooth zippers you can work with cold or gloved hands are worth a lot. Two-way zippers let you open a compartment from either end. Test every buckle and zipper before you trust the pack.
Water resistance vs. waterproof
Most backpacks are water resistant at best. Rain will get in through zippers and seams sooner or later. You have three ways to deal with it:
Choose a waterproof pack. The Rothco Waveguard Waterproof Backpack is listed as a fully waterproof tactical pack, made for wet conditions, river crossings and rainy bug-out scenarios. It's a strong pick if you live where floods or heavy storms are your main risk.
Line your pack. A heavy trash bag inside the main compartment keeps clothes and electronics dry. Put smaller items in airtight plastic bags, which Ready.gov also recommends for kit storage.
Cover the pack and yourself. A poncho can go over both you and your pack. The Rothco G.I. Type Rip-Stop Poncho is a durable option for bug-out bags and vehicle kits, and a poncho can double as an emergency shelter with some cord.
Wet clothing pulls heat from your body fast. If you live somewhere cold, read our cold-weather layering guide and pack a dry layer in a sealed bag.
Step 5: Organization and Features That Actually Help
A pack full of loose gear wastes time. Good organization means you can find what you need fast, even in the dark or under stress.
Compartments and pockets
Look for a main compartment for bulk items, at least one quick-access pocket for things you'll grab often (light, map, snacks, phone battery), and side pockets or sleeves for water. A top or front pocket for your first aid kit makes it easy to find.
MOLLE webbing
MOLLE is a grid of webbing that lets you attach pouches to the outside of a pack. It's useful for a trauma pouch, a canteen or a radio. The danger is overdoing it. Every pouch adds weight and snag points, and a pack covered in gear gets heavy fast. Add pouches for a reason, not because the webbing is there.
Hydration sleeve
Many packs have an internal sleeve for a hydration bladder. Sipping from a tube while you walk helps you drink regularly. Just remember that a bladder can leak and is hard to refill from a stream, so pair it with a bottle or canteen.
Step 6: The Gray Man Question
Some preppers worry that a camo military pack draws attention in a crowd or a shelter. That's a fair point. A plain dark pack blends in better at a bus station or an evacuation center than a pack covered in patches. On the other hand, tactical packs are often more durable and better organized.
There's no single right answer. Think about where you'd most likely go. If it's an urban shelter or a relative's apartment, a solid black or gray pack with the MOLLE left mostly empty draws less attention. If you'd be heading into rural or wooded areas, coyote or olive tones work fine.
How to Pack Your Bug Out Bag Backpack
How you load the pack changes how it carries. A simple order that works for most packs:
Bottom: soft, light items you won't need until you stop, like a sleeping layer or spare clothes.
Middle, close to your back: the heaviest items, such as food and water. Keeping weight close to your spine and centered helps your balance.
Top: your rain layer, a warm layer and your shelter items, so you can get to them fast when the weather turns.
Outside pockets: first aid kit, flashlight or headlamp, map and compass, phone battery, snacks and hand sanitizer.
Ready.gov's kit list is a good starting checklist: water, food, a flashlight, a first aid kit, extra batteries, a whistle, a dust mask, local maps and a phone charger and backup battery. Add prescription medications, copies of important documents in a waterproof bag, cash and a change of clothes and sturdy shoes. For a fun, family-friendly way to go over the list, see our post on the CDC's real zombie apocalypse preparedness guide.
Keep reading: for the item-by-item list, see our Bug Out Bag Checklist: What to Pack for 72 Hours. If wildfire is your main risk, our Wildfire Evacuation Checklist covers what to grab and when to leave.
Keep It Ready
A bug out bag only helps if it's ready to go. A few habits keep it that way:
Store it where you can grab it in seconds, like a closet near the door. Make sure everyone in the house knows where it is.
Check it twice a year. Rotate food and water, replace expired medications and test the batteries. The start and end of daylight saving time are easy reminders, and our daylight saving time kit checklist walks through it.
Update it with the seasons. Swap in warmer layers for winter and lighter ones for summer.
Practice once. Grab the bag and walk out the door on a timer. You'll quickly learn what's missing or what's too heavy.
Bug Out Bag Backpack FAQ
What size backpack is best for a bug out bag?
For most adults, a pack between about 35 and 50 liters holds three days of essentials without getting too heavy. Go smaller for a car or get-home bag, and bigger only if you carry extra gear for kids or cold weather.
How heavy should a bug out bag be?
REI's backpacking guideline is a loaded pack of no more than about 20 percent of your body weight, so about 30 pounds for a 150-pound person. Treat that as a starting point and do a real carry test with your own kit.
Is a military-style pack better than a hiking backpack?
Not always. Tactical packs tend to be tough, with lots of organization and MOLLE webbing. Hiking packs are often lighter, with better hipbelts for long walks. Pick the one that fits your body, holds your kit and that you can carry comfortably.
Should my bug out bag be waterproof?
It should at least keep your gear dry. You can use a waterproof pack, line a regular pack with a heavy trash bag, or carry a poncho that covers you and the pack.
Do I need a prebuilt kit or an empty pack?
An empty pack lets you choose every item and fit the bag to your body. Either way, open it, learn what's inside and add your own medications, documents and clothes.
The Bottom Line
The best bug out bag backpack is the one that fits your torso, carries most of the weight on your hips, keeps your gear dry and holds about three days of essentials without getting too heavy. Measure yourself, lay out your kit, pick a pack sized for it, and test it on a real walk. Then store it by the door and check it twice a year.
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