How much food you have divided by how much you eat in a day/week/ month/ unit of time.

How many batteries you have divided by how many you use in a unit of time. It's just math.

When I say prepped for 9 months, it means I have actually kept track for 2 years what my family eats, and planned to have enough dry goods, canned, preserved, frozen foods, etc to support the core meals and snacks we would have for around 7 months, and enough freeze dried food and fresh food to extend that to 9 months.

That's not counting the garden, orchard, or any hunted meats.

Without actually looking at what your family eats, you will often fall into the trap of prepping food, but not having meals the family will eat.

For instance,

Breakfast was pancakes made from staples that are all shelf stable, except for fresh eggs (powdered eggs are a substitute if needed)

Lunch was frozen fruit smoothie and sandwiches with cut up fresh veggies, not very shelf stable today, but the bread was fresh baked and the salami and summer sausage was home made from last year's side of beef and pork order. The cheese was bought as was the veggies, but the fruit was frozen from last year's harvest

tonight's dinner is pot pie, we have canned chicken stock (better than bullion is the shelf stable longer term backup), frozen chicken (freeze dried is the long term backup), frozen vegetables (canned and freeze dried are the two backups), pastry (made from staples we store large quantities of for bread), and some spices.

It's different to say what do I need to make for pot pie, than do I have enough calories to last that long, which you could do with peanut butter and crackers.

So that's why I recommend making a list for a long time, preferably for two years so you understand the seasonality of it, and then find what you need to make your meals from shelf stable items

Ideally, you'll adjust both your meal planning, and your storage to make the best of both worlds. Meals that are easier to make from shelf stable or otherwise preserved foods, and storing more items that can be used across a lot of varied meals.

There's a ton of Mexican/texmex type meals that can be made with beans, rice, corn (made into masa for a lot of recipes), seasoned meat, and then addition of fresh ingredients as one large category

Same thing with supply items, find out how much TP, soap, paper towels, water softener salt, toothpaste, etc, everything you use, tracking by copying down receipts is an easy way for us, then marking how long it lasted and plan accordingly. We have 12 months for most of this sort of thing because they're so shelf stable

The first step is to figure out how much food you eat in a day now and then think about how much you need to eat if things get fucky.

For me personally, I do the deep pantry approach where I estimate I have 2-3 months of food available at any given time. I know what I go through in a week, so it's not hard to guess what I need for 8-12 weeks.

But if you seriously have no idea how much toilet paper or toothpaste you go through, figuring that out is a good place to start.

Easiest way by far is to track how much you're eating and store multiples of that. I've got a one year supply of frozen meat in a chest freezer in the basement that runs off solar if the power goes out. I've got a one year supply of dried beans, rice, freeze dried veggies, powdered egg, powdered milk, shelf stable oils, flour, sugar, and a rain barrel and filtration system that, as long as I get about 2 sunny days per week, I should be good about one year without needing to leave my house or fire up my generator. For which I have 30 gallons of stable ethanol free gas.

Most of my pantry is surrounded by meals. I make sure I have the ingredients for certain meals. I made a a menu of meals I like and enjoy. I try to have enough stuff to make most of those meals at least 3 times. That is how I do it. Some things I estimate it based on available space. I live in a small apartment. When the area desinated for a certian item or catorgory of items is full then I am done. I just try to top it off from there. I started by keeping track of how often I eat different ingredients and how much per month. Then do math from there

For example if I want to have a taco tuesday/mexican themed night once a week . I need to have at least 4 cans of corn, 4 cans of refried beans, 4 boxes of mexican or spanish rice. I need tortillas stocked in my pantry. I need meat either in my fridge or in canned form. I also have things like olives,salsa, hot sauce,etc. My favorite meal is loco moco. So I try to have brown gravy in my pantry in some form. Ground beef in my freezer. I also have some canned. I have rice to put the hamburger gravy on. If times are good I also have eggs to put on top. That will do me for a month. I do muplication to get to my goal of 3,6, or 12 months. I do this with about 10 meals on my menu each month to keep things interesting

The basic formula is:

Days of Food Supply = Calories Stored / Calories Consumed per Day

Common rough estimates of calorie usage are around 2,000 calories per day per adult, with specifics varying wildly. Athletes can be 4x that (ex. 8,000), and strenuous physical activity that may be required in SHTF could get you close to that potentially. If you want a more accurate assessment of how many days of food you have, you'll first need to evaluate your real world calorie usage under similar exertion as you expect for the problems you are preparing for.

At least in the US, foods are required to have labels that indicate how many servings are in the container and how many calories are contained in each serving. From those values you can calculate the calories per container.

Calories per container = Servings per container * Calories per serving

As a side note, don't mistake "servings" as being equivalent to "meals", as that's not at all what that means. A "serving" is just a typical portion size, usually as a subset of a larger "meal". So, you can pretty much ignore "servings" other than as described above when needing to use that to convert the given values into something more useful.

As a specific example, lets imagine you have a lot of cans of soup, with many being Campbell's Chicken Noodle or similar. The label indicates "2.5 Servings Per Container" and "60 calories per serving". Using the above formula, that means each can provides about 150 calories. If you have determined by tracking your real world calorie intake that you expect to use 1,500 calories per day, that means you'll go through 10 cans a day. Put another way, every 10 cans represents 1 day of prepped food.

From a practical perspective it gets overwhelming quickly to be very precise. I tend to do a lot of very rough approximation and lots of grouping together of roughly similar items. By reducing the complexity to a dozen or less such groupings, I can rather quickly and often run an updated estimate on my total prepped food timeframe.

I built a spreadsheet... item, count, package size, calories. Let the spreadsheet math it all out and divide by however many calories per day you think you need for your tribe. Keep it updated and you have your inventory and a way to see obvious places to increase if you want to add to your covered time.

Rechargeable batteries can solve the battery problem. Bandaids and Motrin are relatively cheap, so it's tough to keep too many. If it's something that doesn't go bad like TP, soap etc... I just make sure I've got multiple spares. To get more specific than that, you'd need to start tracking your purchases and see how frequently you have to restock currently.

Ask the person who grocery shops and cooks in your house.

Or… gather several months of receipts and average from there

spreadsheet tracking and time

Disasters are messy and you can't really plot your survival on a spreadsheet. I have a pantry, which I keep full and rotate, but its actual calorie value is always changing as I buy different things. I have a ridiculous amount of rice which I can use to stretch my other food. How much rice can I add to a can of soup and still want to eat it? I'm sure it will depend on the situation. I also have a garden. In the fall I can survive on mostly my own produce. In the winter I can still eat winter squash or dig up potatoes or sunchokes, but how many calories are available? I have no idea. The neighbors know I have a garden and they might want some food too. No spreadsheet will capture all these variable. I would say that your food storage should mostly consist of a pantry that you rotate and eat from every day, and it should be as big as you can realistically make it in the space you have.

For non-perishable supplies, I generally go completely overboard and buy way too much. I may want to share it with the neighbors, but as long as it doesn't expire I figure I'll use it eventually. I have enough laundry soap for two apocalypses.

I use to buy a lot of alkaline batteries and most of them ended up going bad in storage. Today most of my critical equipment has a built-in Lithium-ion battery which I can recharge from my big battery "solar generator". I have some rechargeable AA batteries for things that still need old-timey batteries.

I have a wife and 2 kids. I try to think of being able to eat 2x times a day. At least for them. So of I'm looking at my stock of canned soups, how many days do I have with that current stockpile. I also wonder what do I have to add to those cans to make them more calorie rich, and filling.

I have about a month's worth of supplies. Things usually happen suddenly, but after a week everything becomes clear and you can either replenish your supplies or decide to run away.

I counted each family member and multiplied that times 2,000 and then multiplied that times 365. So my initial goal was 2,000 calories per person per day. The base of our food storage is shelf stable grains and legumes. The grains last far longer than the legumes. Everything is stored in mylar bags with oxygen absorbers in 5 to 6 gallon food grade buckets. I have a wall of buckets many layers deep stacked high and put a curtain across the room to hide it.

I keep fresh yeast in the fridge so we always have enough for a year's worth of bread and baked goods. And I keep thousands of cans or jars of fruit, veg, meat and seafood. It's been a few years since I really calculated those out past my initial goals. But I try and take stock and buy more of what we are using most of and then keep building up stock. Every paycheck I spend part of the grocery budget on shelf stable foods. A couple of cases of coconut milk here, a case of tomato paste there, a case of canned clams, chicken or tuna.

I try and keep a year's supply of garden seeds and supplies on hand. And we have a very extensive garden. I was very sick this past year and didn't get much done so I'm playing catch up now in January weeding and mulching beds. I also basically have everything I need to grow what we can: two hoop houses and the greenhouse plastic to cover in winter. Many raised beds with pvc piping and garden row cover to extend the growing season, large grow light sets up inside, heavy duty seed starting trays and 6 packs.

Whether job loss or societal chaos the garden is always a huge part of my back up plan. I just started two large trays of leeks and onions this afternoon and popped them under my grow lights. I love how I can stuff a leek plant in the ground, mulch it and neglect it and it just sits there slowly growing till I need it with very little upkeep needed at all.

I have gallons of oils and honey, buckets of salt and sugar. I am weak on the dairy storage since the shelf stable stuff doesn't last long and powdered milk in 2020 made my small children actually cry at the taste. LOL

Basically we started with a minimum based on calories and just try and stock more. We don't always do a good job. I am currently really low on TP.

Add up calories and protein for 1 month. Multiply by 12….

For household items I look to see how much I use in 3 months

i made a spreadsheet with each food, the #  i have, and their calories (ie 10 cans of soup x 500 cal in a can), and totaled it up then divided it by 2000 cal per day per person 

Research

You Store What You Eat and Eat What You Store

So only you know what canned food you need to store.

You might want to watch [this lady ](https://www.youtube.com/playlist?list=PLR2Rfb0hgP0X7lGQhzixmIXQha6xt6KGK and how she explains food storage and how to know how much you need for 1 week or 2 weeks. There are several videos and each will have different information She would give different lessons based on what her class always knew and the area they lived in. So if she was talking to those in a city with no areas for gardens, she didn't cover canning veggies yourself. In farmland, she gave different talks. So there are several videos in the playlist with little bits of different information in each talk. And she was an LDS teacher so ignore all of the religious rhetoric.

Base it off calories for food.

2400 for male and 2000 for female.

So I would need 72,000 calories of stored food to last 30 days for just me.

First aid you buy the basics. Dont go overboard as it will just expire. 

TP buy based of current usage. 

Batteries just do rechargeable. 21700, 18650 and AA. Enough for replacements and to use all devices. 

Our food situation is divided into 3 categories:

Fresh/frozen: will last up to 2 weeks.

Canned/dry goods: will last 2 weeks to 6 months.

Dry canned/dehydrated: will last 6 months to 3 years.

Coffee (and coffee condiments) gets its own category. 

We did a recent move  and downsized some old stock. But I am actively building up supplies in all 3 categories. 

It helps to write down what you're getting low on. Then go out and buy 3 or 4 of an item to replace it.

I have a garden at home and at my bug out location, I do canning at home. I have 3yrs worth of food for myself.

I use a spreadsheet to track long-term food storage, it includes calories.

I don't do if for out deep pantry where we are pulling from daily, (too much of a pain) only for foods I have in my "set it and forget it" storage. So for deep pantry I just guesstimate an additional month or so. I also have a column for best by date so I know when to pull and rotate/replace.

My issue is the 3 elderly adults and a couple of adult kids I’ll need to feed. While we have a list of everything, I can’t predict consumption with the additional mouths. I guess it’s one meal per day, lol

so i wrote some software exactly for this reason. I have currently finished and am selling offline software that tracks food and water inventory and provides estimated projections of days in a comfort or survival mode. It works off a usb, on a raspberry pi (prepper disk), or any system running linux. the food and water app has done ok, so far and i am working on a few more for things like guns, med supplies, logistics, and comms stuff. eventually i will have a full suite of tools that run as very lightweight binaries and databases without any need for internet. i dont want to break the rules and shill it here, and most of them are still in development. Tho I am looking for a few beta testers for upcoming apps (not sure if thats ok to ask here, will remove if its not ok).

A military aged male engaged in strenuous work requires about 3100 calories per day. This is how I count my food preps. Since that is about the maximum anyone should require my food will out last my estimates.

Humans need about 1,200 kilocalories per day. This is the bare physiological minimum. If you consume less than that, your body is drawing energy from fat reserves, which is not sustainable in the long term. I use the bare physiological minimum in my calculations because, in reality, there are usually alternative ways to obtain food. There is almost always some food available in the woods. So calculating how many calories you have is straightforward. You read the number of calories on the label and multiply it by the number of cans you have. The average human consumes about 2,000 kilocalories per day. There is a clear difference between average consumption and the bare physiological minimum.

Caloric intake need vs calories stored

Also consider: will you be more physically active in a prolonged emergency? If so, youll need to account for that.

Fitness and preparedness go hand in hand friends.

2500 calories a day, 75,000 a month, 900, 000 year. I always round up. 1,000,000 year

Rechargeable batteries and solar battery chargers, then it becomes a calculation on how many spare sets of batteries I need for specific devices, then the charger(s) enough to support them.  At least three sets of rechargeable batteries for each device, plus a lot of general spares.

If u buy from the grocery store, 3-4 years max. If you buy freeze dried meals, “not the stuff from Walmart” they will last 20-25 years. If you regularly eat the basics of prepping u can “rotate” them if you have the organization. We rotate our rice and beans constantly eating them then replacing. Canned goods like tuna and chicken we also rotate but I donate them a year b4 expiration. Personally I hate the stuff.

Count calories in the food and look up a calorie chart and figure out how many calories each person you are prepping for needs.

I store a lot of grains and beans. I plan on 2 pounds per person per day. That averages out to 3400 calories per person per day. That is WAY over kill. But it allows for loss such as sifting flour after grinding or removing the hull of corn when nixtamuluzing it.

Can of soup = 1 meal

Box of pasta n = 1 meal

Can of chicken = 1 meal

Yeah, I’m gonna be mixing all 3 together into a big pot, but that’s still only 3 meals whether 3 for me or 1 each for 3 people.

I expect 3 meals a day especially in a crisis.

It’s not a big meal. It’s enough the minimum to survive. One bowl of food will be a meal.

200 cans of soup, 140 boxes of pasta, and 60 cans of meat gives me a minimum of 60 “quality” meals plus another 100 or so of “good enough” meals.

Family of 4, this is 160 meals, at 12 a day means I have about 2 weeks of meals using just this.

I also have bags of flour, beans, rice, etc to supplement.

I have a pretty accurate spreadsheet, I threw it all into an LLM and it did a pretty good job of making sense of it all.