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The buffer that keeps an emergency off a credit card.
The emergency fund question is two numbers: how much, and how long to get there. This calculator computes both from your real essentials — rent, utilities, food, insurance, minimum debt payments — with coverage targets matched to your situation: 3 months for stable dual incomes, 6 as the standard, 9–12 for single incomes, kids, or commission pay. Then it turns your monthly savings rate into a finish date.
People use it after the scare — the car repair that went on a card, the week of missed shifts — when "I need a buffer" needs to become a number and a finish date. It is also the first calculation in any financial reset, because everything else (debt payoff, investing) assumes the next emergency is already paid for.
Essential monthly expenses times your coverage target. At $3,500 in essentials: $10,500 for 3 months (stable dual income), $21,000 for 6 months (the standard advice), $31,500 for 9, $42,000 for 12 (variable or commission income). Only essentials count — the fund covers survival, not lifestyle.
In stages. Grab the full employer 401(k) match first (it is an instant 50–100% return), then a $1,000 starter buffer so small emergencies stay off the card, then attack high-interest debt, then finish the full 3–12 month fund. A $3,500-essential household saving $800/month closes a $16,000 gap in 20 months.
A high-yield savings account — liquid, FDIC-insured, and paying meaningful interest. Not invested: the fund's job is to be there on the worst day, which is exactly when markets are down. Not checking: a small barrier between you and a "mergency" is a feature.