Emergency Fund Calculator
How large an emergency fund should be for your circumstances, how long it takes to build, and how long the current one would last.
The conventional target is three to six months of essential expenses — not income, and not total spending.
How the emergency fund calculator works
The conventional target is three to six months of essential expenses — not income, and not total spending. Essentials are what you cannot stop paying: housing, food, utilities, insurance, minimum debt payments and transport.
The right number inside that range depends on how replaceable your income is. A dual-income household in a stable sector sits at the low end; a single earner on commission or contract belongs at the high end or beyond.
Formula: target = essential monthly expenses × months of cover
Worked examples
| Inputs | Target fund | Note |
|---|---|---|
| 4,200 expenses, 6 months target | $25,200.00 | 25,200 target, about 3 years to build |
| Three months instead | $12,600.00 | a far nearer target |
| Already funded | $25,200.00 | fully covered |
FAQFrequently asked questions
How big should an emergency fund be?
Three to six months of essential expenses for most people. Nine to twelve if your income is variable, contract or self-employed.
Expenses or income?
Expenses, and only the essential ones. The fund exists to cover what you cannot stop paying, not your whole lifestyle.
Where should it be held?
Somewhere accessible within a day or two and not exposed to market falls — the point is availability, not return.
Should I build it before paying off debt?
A small starter buffer first, then high-rate debt, then the full fund. Without any buffer, the next surprize goes back on the card.
Does the interest matter?
Barely, at this scale and horizon. This page shows what it adds so you can see for yourself.
Where these figures come from
- CFA Institute — Quantitative Methods: The Time Value of Money — the discounting, annuity and IRR conventions used here
- US Federal Reserve — Regulation Z (Truth in Lending), APR calculation — why APR includes fees where a nominal rate does not
- Consumer Financial Protection Bureau — the US consumer finance regulator
Last checked: September 2026. These are the standard textbook formulas; the conventions named are those of the CFA Institute curriculum and ISO 80000 usage.