Its usually recommended to have 3-6 months of expenses in the event of income loss, but its only a rough guideline. In some industries or economic scenarios, you may go almost 12-24 months with a job or significant income (I leave out part time jobs or gig for keeping this simple).
In short, we don't save enough in America (for a variety of reasons), and we don't have a proper social safety net for when that comes back to bite us.
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Have 6-12 months of expenses saved in your emergency fund. This is critical. When possible max out your retirement accounts (a Roth IRA can be used as an emergency fund in a pinch; contributions can be removed at any time penalty fee, but this should be a last resort). Save more. Live below your means.
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https://www.reddit.com/r/personalfinance/wiki/commontopics
Infographic: https://i.imgur.com/fb7Dtmh.png