 you might think about having an amount enough to cover the absolute bare necessities for two months. Bare necessities include a minimum housing payment, food staples, batteries, water, gas, and basic living needs. The most recent survey from the Bureau of Labor Statistics reports that the average monthly cost for food and gas alone is slightly less than a grand. That could serve as a baseline for how much to keep in cash, which would also vary depending on the size of your household.