Your Emergency Fund Is Probably the Wrong Size

"Three to six months" is repeated so often that it has stopped sounding like a guess. It is a guess. It ignores every variable that would actually change the answer — how stable your income is, how many people depend on it, what your insurance covers, and how quickly your spending could fall if it had to.

What the fund is actually for

An emergency fund is not a savings goal. It is self-insurance against income interruption and unplanned expenses, and its correct size is a function of two things: how likely the interruption is, and how long it would last.

A rough derivation

Start with your floor spending — not current spending. Housing, food, utilities, insurance, minimum debt payments, transport to work. For most households this is meaningfully below the monthly total, because the total includes things that would stop immediately in a crisis.

floor_monthly  = essential spending only
months_needed  = expected time to replace income
buffer         = floor_monthly × months_needed

Then adjust months_needed for reality:

• Two stable incomes, in-demand skills, no dependants — the realistic gap is short and partly covered by the second income. Three months of floor spending may genuinely be enough.
• Single income, specialised role, or a small field — replacement can take two or three times longer. Six to twelve months is not paranoid.
• Self-employed or commission-based — the risk is not a cliff but volatility. Size the fund against the worst quarter you have actually had, not an imagined layoff.
• Homeowner, older car, dependants — add a separate line for the non-income emergencies, because those arrive independently of the job market.

Where to keep it

The requirements are unusual for a financial asset: you need it to be boring. Accessible within a day or two, nominally stable, and separate enough from your current account that it does not get spent by accident. A high-yield savings account or a money market fund covers this. What you are buying is optionality, and volatile assets do not sell it.

The emergency fund is the only part of a portfolio where the correct expected return is "slightly less than everything else, and that is fine."

The sequencing question

If you carry high-interest debt, a large cash pile is expensive — you are earning perhaps 4% while paying 22%. The usual resolution is a small starter buffer (enough to absorb a single ordinary shock, so an emergency does not push you further into the same debt), then aggressive payoff, then the full fund. The starter buffer is what keeps the debt payoff from unwinding the first time a tyre blows.

Educational content, not financial advice. Your situation has details this article does not know about.