Food Storage Calculator
There are numerous food storage calculators on the internet, nearly all based on guides prepared by the Church of Jesus Christ of Latter Day Saints. Here is a simplified basic extrapolation of that work to use as a storage planning guide for 1 “average” adult for 1 month. You can adjust for your family accordingly.
Note: 1 gallon per person per day of drinking water can store up to 6 months. https://www.churchofjesuschrist.org/topics/food-storage/drinking-water-guidelines?lang=eng
LDS food storage guides: https://www.churchofjesuschrist.org/study/ensign/2006/03/random-sampler/food-storage-for-one-year?lang=eng
DO remember infant and toddler foods will need to be either stored or made using a non-electric method to puree stored food. DO remember pets. Out-of-the-ordinary conditions and stressed humans are both especially difficult for pets, so make sure you've stored at least a transitional amount of their regular food. Livestock are another consideration.
Additional Resource
Building Up A Well-Stocked Pantry & Long-Term Food Storage Supply