Emergency fund calculator

How big an emergency fund do your monthly costs call for?

The calculator works from two choices you make: what your essential costs come to each month, and how many months you want the fund to carry them. The target is the product of the two, target = essential monthly costs x months of cover. It then takes off what you have already saved and counts how long your monthly saving needs to close the rest.

With the defaults, $3,000 a month of essential costs and 6 months of cover make a target of $18,000. Savings of $5,000 leave a gap of $13,000, and setting aside $400 a month closes it in 33 months, or 2 years 9 months. Today's $5,000 covers 1.7 months of those costs. To close the gap within a year instead, the monthly amount would be $1,083.33.

How do you calculate an emergency fund target?

1. Total your essential monthly costs: the bills that continue with no income coming in. In the default example they come to $3,000.
2. Choose the months of cover: how long you want the fund to pay those bills. The default is 6.
3. Multiply: $3,000 x 6 = $18,000.
4. Subtract current savings: $18,000 - $5,000 = a $13,000 gap.
5. Divide by the monthly saving and round up: $13,000 / $400 = 32.5, so 33 months.

A useful companion figure is the months your savings cover now: savings divided by monthly costs, here $5,000 / $3,000 = 1.7 months. It moves the moment costs change, which is why the calculator shows it beside the target.

How many months of expenses for an emergency fund?

There is no single right number, and the calculator treats it as your choice. Two government consumer agencies put it this way, as read on 14 November 2026:

• The Financial Consumer Agency of Canada, in its guide Setting up an emergency fund (page dated 20 October 2025), suggests saving the equivalent of 3 to 6 months of your regular expenses, or alternatively 3 to 6 months of income, and says to choose whichever method is easier.
• The US Consumer Financial Protection Bureau, in An essential guide to building an emergency fund (last modified 29 October 2025), gives no number of months: it says the amount depends on your situation and suggests looking at the unexpected expenses you have had before and what they cost.

On the default $3,000 of monthly costs, the choice moves the target a long way:

The Canadian guide speaks of regular expenses, which can include spending you would cut in an emergency; this calculator asks for essential costs, which gives a smaller target for the same number of months. To follow the income version instead, enter your monthly income in the costs field.

How long will it take to build an emergency fund?

Divide the gap by what you set aside each month and round up to whole months. For the default $13,000 gap:

Working backward from a deadline, the monthly amount is the gap divided by the months available: $13,000 over 12 months is $1,083.33 a month, and over 24 months $541.67. Halving the monthly saving roughly doubles the time, as the $200 and $400 rows show, because without interest the relationship is a straight division. If you set nothing aside each month, the calculator says the gap stays where it is and shows the amount that would close it in a year.

Does interest on the fund change the time?

A little. Open Interest on the fund and enter the annual rate you have been offered; the calculator adds the rate divided by 12 on the balance at the start of each month and then adds your saving at the end of the month. Using the defaults:

• At 0% the target is reached in 33 months.
• At 2% it takes 32 months, with $609.92 of interest along the way.
• At 4% it takes 30 months, with $1,123.39 of interest.

Interest helps more as the fund grows, but on a goal measured in months of costs it shortens the wait by a few months here rather than years; the monthly amount set aside does most of the work. The calculator shows interest before any tax on it, and it does not raise your costs for inflation, so a fund built over several years may need topping up once it is reached.

Worked examples in three currencies

Every currency uses the same multiplication and division, and nothing is converted. These households are illustrations.

The pound example's gap of £10,200 divided by £350 is 29.1, so it takes 30 months. The dirham household chose 3 months; its AED 26,000 gap divided by AED 2,500 is 10.4, so 11 months. When the division comes out exact, as with a €6,000 gap and €300 a month, the answer is exactly 20 months with no partial month.

Which monthly costs count as essential?

The calculator takes a single figure, and you decide what goes into it. A workable test is whether the cost would continue if your income stopped tomorrow and you cut back hard. Examples that pass that test:

• rent or mortgage payments, property tax and home insurance;
• utilities, phone and internet you need to look for work;
• groceries and essential household supplies;
• health, car and life insurance premiums;
• transport, childcare and minimum payments on debts.

Subscriptions, eating out, travel and new purchases are examples of costs that can be paused. The narrower your essentials figure, the smaller the target and the sooner it is reached, but it also means a tighter budget while the fund is in use. Irregular bills, such as an annual insurance premium, can be included by dividing the yearly amount by 12.

How do you build an emergency fund calculator in Excel?

Put essential monthly costs in B1, months of cover in B2, current savings in B3 and the monthly amount in B4. Then:

• Target: =B1*B2 returns 18,000 with the defaults.
• Gap: =B1*B2-B3 returns 13,000; treat a negative result as zero, meaning the target is already met.
• Months with no interest: divide the gap by B4 and round up to the next whole month: 13,000 / 400 = 32.5, so 33.
• Months with interest: Microsoft documents NPER(rate, pmt, pv, [fv], [type]); =NPER(4%/12, -400, -5000, 18000) returns 29.73, so the target is reached in month 30, matching the calculator at 4%.

In the NPER formula the savings already held and the monthly amount are entered as negative numbers because they are paid in, and the target is the future value. Leaving type out means each deposit lands at the end of the month, the same timing this calculator uses.

Common mistakes and what this calculator leaves out

• Counting all spending as essential. It inflates the target; count what would continue in a crisis.
• Counting money that is not available quickly. Savings locked in a fixed term or invested in assets that can fall in value may not be there when needed.
• Forgetting to refill the fund. After it is used, the gap opens again and the same arithmetic applies.
• Leaving the target fixed for years. When monthly costs rise, so does the target.

The calculator assumes your monthly costs and the amount you set aside stay the same, and that any interest is added monthly at a fixed rate before tax. It does not adjust for inflation, income from benefits or insurance, a partner's income, or one-off costs larger than a month's spending. It counts up to 50 years and does not choose the months of cover for you.

Glossary

Emergency fund: money set aside for unexpected costs or a loss of income. Essential monthly costs: spending that continues when income stops. Months of cover: how many months the fund would pay those costs, a number you choose. Target: monthly costs multiplied by months of cover. Gap: the target minus what is already saved. Months covered now: current savings divided by monthly costs. Interest rate (annual): the yearly rate on the fund, applied here monthly at one twelfth.

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