There’s a simple rule of thumb for figuring out how many days of food you can fit into a bear canister. Find out the capacity of your bear canister in cubic inches and divide by 100. That will give you a pretty good approximation of the number of days of food you can cram into it. For instance, if your bear canister has 500 cubic inches of capacity, you should be able to fit 5 days’ worth of food into it.
See the table below, where I’ve precomputed the number of days for all of the popular bear canisters and Ursacks bear-proof bear bags that backpackers and campers use where bear-resistant containers are required.
When packing your food, your goal is to fill up every nook and cranny inside the canister so that it is full of food without any gaps between items. For example, you’ll want to move it out of hard-sided containers, like boxes, and repack it with “soft” containers like plastic sandwich bags that will pack flat or will flow around other items. For example, oatmeal, nuts, rice, beans, m&ms, etc., are best repackaged without the boxes or extra packaging they often come in. The same is true of freeze-dried Mountain-House-style meals, which come in bulky rehydration bags. You can move them to a small plastic bag and rehydrate the contents in a cookpot, kept warm with a cozy or your sleeping bag, instead.
Make sure to leave some room in your bear canister for the other “smellables” that you need to pack away at night, including your toothpaste, scented lotions, etc. Basically, if it goes in your mouth or on your skin, it needs to go in your bear canister.
When packing your food, there’s no need to pack your first day’s food in the bear canister, because you’ll eat it before it needs to be stored away. Store it in a smell-proof plastic bag in your backpack, so it doesn’t make your gear smell. People often overlook that first day, but carrying it separately can really extend your range.
Editor’s note: If you’re thinking about buying gear that we’ve reviewed or recommend on SectionHiker, you can help support us in the process. Just click on any of the seller links above, and if you make a purchase, we may (but not always) receive a small percentage of the transaction. The cost of the product is the same to you but this helps us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides. Thanks and we appreciate your support!