The problem with generic rules
“Three to six months” is a helpful starting point, but it is not a diagnosis. A single renter with stable income and low fixed costs may need a different reserve than a family with children, variable income, medical expenses or an older home.
Start with fixed survival costs
List housing, utilities, groceries, insurance, minimum debt payments, transport and basic family obligations. Ignore restaurants, upgrades and discretionary shopping for this calculation. The goal is not to preserve your normal lifestyle. The goal is to preserve choices.
Adjust for income risk
If your income is steady and replaceable, a smaller reserve can work. If your income is commission-based, seasonal, freelance or tied to one client, the buffer should be larger. The more fragile the income, the more cash buys time.
Keep it separate
Emergency cash should not sit in the same account as everyday spending. The best reserve is visible enough to trust but inconvenient enough not to raid for normal purchases.
Review twice a year
Your reserve target changes when rent, family size, debt, income stability or insurance deductibles change. Revisit it every six months and after major life events.