Montana emergency fund calculator

What counts as essential spending

The first field is the one people fill in wrong. It asks for essential spending, not total spending, and the difference is usually 20% to 30% of a budget.

Essential means what it costs to keep the lights on if income stopped tomorrow:

• Rent or mortgage, and the property tax and insurance attached to it
• Utilities, phone and internet
• Groceries, not restaurants
• Insurance premiums, including health cover you would have to buy yourself
• Minimum debt payments, not accelerated ones
• Childcare and transport you cannot drop

Excluded: holidays, subscriptions, gym, savings contributions, the extra you pay on the car loan. In an actual emergency those stop, and a fund sized to keep them running is a fund that took two extra years to build for no reason.

Build the figure from three months of bank and card statements rather than from memory, which reliably understates it. Go through the transactions once, mark each as essential or not, and total the essential column for each month. Take the middle of the three rather than the lowest, then add back the bills that do not arrive monthly: an annual insurance premium, a car registration, a quarterly water bill. Those are easy to forget precisely because they are absent from the month you happen to be looking at, and they are exactly the sort of thing that lands in a bad quarter.

How many months do you actually need?

The six month rule is a default, not a finding. What it is really estimating is how long it takes you to replace your income, and that varies more than any other input on this page.

Two other things push the number up: a specialised job in a thin local market, and a household where both incomes come from the same employer or the same industry. The Federal Reserve's household survey has consistently found that about a third of adults could not cover a $400 emergency with cash, so the starting point for most people is not choosing between six and nine. It is getting past one.

A worked example on the defaults

The defaults are $3,400 of essential spending a month, six months of cover, $5,000 saved and $400 a month available.

Three years is a long time, and seeing it stated plainly is the point. Most people respond by lowering the target to three months first, hitting that, and then continuing. A fund at one month is a different life from a fund at zero, and the gap between one and six matters less than the gap between zero and one.

A second run, at other levels of cover

The months field is the one people agonise over, so it helps to see what each choice actually costs in time. Same $3,400 of essential spending, same $5,000 already saved, same $400 a month:

The twelve month row is the one that changes behaviour. Self-employed readers are told to hold a year of cover, and on these inputs that is a seven and a half year project. The usual response is not to abandon the target but to attack it from the other side: hold the fund in a separate account, add irregular income to it in the good months rather than a flat $400, and treat the flat figure as a floor rather than the plan.

Note also what the timeline does not do. It divides the gap by the monthly amount and stops there, crediting no interest along the way, so a fund earning a real savings rate arrives slightly sooner than the table says. That understatement is deliberate. It is the safer direction to be wrong in.

Should you save this before paying off credit card debt?

Most planners split the difference rather than choosing. Build a one month buffer first, so the next surprise does not go straight back onto the card, then attack a balance at 20% or more, then finish the fund.

The arithmetic behind that is simple. A savings account paying 4% against a card charging 22% loses 18 points a year, so every extra dollar parked in savings while the card runs is a dollar going backwards. The buffer is worth its cost anyway, because without it the cycle never breaks.

The case against going debt-first entirely is about access rather than arithmetic. Money used to pay down a card is gone: it is available again only if the issuer leaves the limit open, and limits get cut in exactly the conditions that produce emergencies. A household with no cash and a repaid card can end a bad month with neither. That is the whole argument for the buffer, and it is why the split is a sequencing decision rather than a choice between two strategies. The order matters much less than doing both, and someone paying the minimum on a 22% balance while building a six month fund has chosen the most expensive version of being careful.

Where the fund should sit

Somewhere boring and instant. A high-yield savings account at a bank you do not use for daily spending is the standard answer: insured, same-day or next-day access, and one step of friction away from being spent.

It does not belong in the market, where the year you lose your job and the year the market falls have an unhelpful habit of being the same year. It does not belong in a CD you cannot break without forfeiting interest, though a partial CD ladder is defensible once the fund is large and fully funded.

Two details decide whether the account works when it is needed:

• How long a transfer takes. An external transfer commonly takes one to three business days, and a weekend or a holiday stretches that. Test it once with a small amount so you know the timing before it matters, and keep a week or two of spending in the account you actually pay from.
• Whether it is a deposit. An FDIC-insured savings or money market deposit account at a bank is covered to the insured limit. A money market mutual fund held at a brokerage is an investment rather than a deposit and carries no deposit insurance, whatever the name suggests. Credit union accounts carry equivalent NCUA cover.

Splitting the fund across two institutions is worth doing once the balance is large, both for the insurance limit and because an outage or a frozen account at one bank should not take the whole fund offline. More on where cash belongs is in our banking section.

The mistakes people make

• Sizing it on total spending. This is the big one, and it inflates the target by a third.
• Keeping it in the checking account. Money you can see at the supermarket is money you will spend.
• Counting a credit card limit as an emergency fund. A line of credit can be cut, and it is debt in the moment you can least afford new debt.
• Refusing to spend it. A fund that survives a real emergency untouched has failed at its job.
• Never resizing it. Rent goes up, a child arrives, a job changes. The target moves with essential spending.

Where this target stops being the right one

From the tool's own caveats:

• It is built on essential spending, not total spending. The point is what it costs to keep the lights on, not to keep your life unchanged.
• The money belongs somewhere boring and instant, a high-yield savings account rather than the market and rather than a CD you cannot break.
• If you carry credit card debt at 20% or more, most planners would split the difference: a one month buffer first, then the debt, then the rest of this.

The tool also cannot see your household. Severance, a partner's income, unemployment insurance in your state and a parent who would take you in are all real, and all outside the arithmetic. Nothing here is advice about your own circumstances. See the disclaimer, and the rest of the tools in the calculator index.

A checklist

• Add up essential spending from three months of statements, not from memory.
• Pick the months of cover that match how long your job would take to replace.
• Open a separate insured account and move the existing balance into it.
• Automate a transfer the day after payday, however small.
• Hit one month first, then three, then the full target.
• Re-check the target whenever rent, childcare or insurance changes.