You'll want to store more food, or develop long-term solutions, the longer you expect the food shortage to last. Due to the climate change crisis rapidly putting our earth under fire, it is safe to make the assumption that a long term storage option may be the best. The amount of food you want to put in storage should also be determined by how many people you will be providing for. A bigger family will need a lot more than an individual.
Take into consideration your typical food intake for an average week. Then multiply that by three to understand how much you need per month. Looking back at previous food shortages in our country and current shortages across the globe and how long they last/have lasted can also help you figure out just how much you should be stockpiling.