How big does your emergency fund actually need to be?

How this calculator works

The arithmetic is deliberately boring. Your seven expense lines get added into one monthly essentials figure. That figure gets multiplied by a months number between three and six, chosen by your answers about household income and how predictable it is. That product is your target. Your current savings divided by monthly essentials is your coverage. Target minus savings is your gap, and the gap divided by your monthly contribution is your timeline, rounded up to a whole month.

Worked example, using the numbers the page loads with. Essentials come to $3,600 a month: $1,600 housing, $650 groceries, $260 utilities, $420 transport, $280 insurance, $240 in debt minimums, $150 other. Two steady incomes sets the multiplier at 3, so the target is $10,800. With $1,800 saved, coverage is 0.5 months and the gap is $9,000. At $350 a month that's 26 months — a bit over two years. If the same household were living on one variable income, the multiplier would be 6, the target $21,600, and the timeline 57 months. Same bills, same savings rate, more than double the horizon. That is the entire argument for asking about your income instead of printing one number for everybody.

Why the multiplier moves

The three-to-six-month rule is really a bet on how long you'd go without income and how likely that is. A two-earner salaried household losing one job keeps some money coming in and is closing a gap. A single earner on commission has no floor at all, and their income can fall by half without anyone being laid off. Same rule, wildly different exposure. The calculator picks 3, 4, 5 or 6 and tells you which reasoning applied, so you can disagree with it on purpose rather than by accident.

Push the multiplier higher yourself if you work in an industry doing rolling layoffs, if you are the only person in your household with health coverage, if you're self-employed, or if you're over 55 — job searches tend to run longer later in a career. Push it lower if you have a working spouse with separate coverage, a union contract with real severance, or a genuinely liquid backstop you'd be willing to use.

What this calculator ignores, on purpose

It pays no interest on your savings. A high-yield account might earn 4% on a balance that averages a few thousand dollars over two years — call it a couple hundred dollars, or three weeks of contributions. Modeling it would add a decimal point of precision to a number whose inputs are estimates anyway. Open the high-yield account regardless; just don't let its yield change your plan.

It also assumes you never raid the fund, which nobody manages. Real emergency funds go up and down. If yours takes a hit, the timeline stretches and that is the system working, not failing — the fund did its job. Come back and re-run it.

And it assumes your essentials stay flat. They won't. Rent renewals, insurance increases and grocery inflation all push the target up while you're chasing it. Re-run this every January and after any move or job change.

When to ignore the number entirely

If you're carrying credit card debt at 22% or more, do not build a six-month fund first. Get to roughly $1,000 — enough to absorb a car repair without a new balance — then throw everything at the card. A dollar against a 22% balance returns a guaranteed 22%. That same dollar in savings earns 4%. Nothing else in personal finance offers a spread that wide, and the math holds regardless of how anyone feels about it.

If your employer matches 401(k) contributions and you're not getting the full match, capture that before you top off the fund past a month or two. A 50% match is an instant 50% return, and unclaimed match money does not roll over — miss this year's and it's gone.

The one case where you overshoot the target on purpose: a known expense already on the calendar. A deductible you're going to hit, a lease ending, a baby due, a roof at the end of its life. Those aren't emergencies, they're bills with a date on them, and they belong in a separate line rather than quietly eating the fund you built for job loss.

Do this next: open a separate savings account at a bank other than your checking bank, name it, and set an automatic transfer for the day after payday. Separation and automation do more for a fund than any target number.