Enter the monthly costs your household would still need, the income you expect to continue during the scenario, any one-time essential cost, and the number of months you want to test. Add what you already have plus a planned monthly contribution. The calculator returns the monthly income gap, target, funding gap, current coverage when a monthly gap exists, and either a timeline or the reason no finite supported timeline is shown.

The target comes from your inputs. The calculator does not assume that every couple needs the same number of months. Once you have a contribution you can carry, the couples savings-plan guide turns it into a working rule for ordinary and tight months.

Start with a stripped-back month

Use costs you would still need to pay if income stopped or an urgent expense arrived. That often means housing, basic food, utilities, medicine, insurance, essential transport, minimum required payments, and care. It may also include support you have committed to provide to another household.

Look at actual statements before choosing the number. A normal month can hide annual insurance, seasonal energy, school costs, repairs, or medical spending.

An emergency-fund amount depends on the household's situation, and even a small reserve can help absorb an unplanned expense. The CFPB's emergency-fund guide explains both points and defines the fund as cash reserved for unplanned expenses or financial emergencies.

For a couple, the awkward question is whose emergency you are modeling. The dependable-income field makes the difference calculable. Test more than one case:

  • the smaller income stops
  • the larger income stops
  • both incomes drop for a shorter period
  • a large essential cost arrives while income continues

Enter only income expected to continue in that case. Add a one-time essential cost when the scenario involves an urgent repair, travel, insurance excess or deductible, temporary care, or another cost not represented by the monthly gap. The same savings balance can look very different under each case.

The calculator's formulas

The target equals one-time essential costs plus the positive difference between essential monthly expenses and dependable monthly income, multiplied by the chosen buffer months.

monthly income gap = max(0, essential monthly expenses - dependable monthly income)

target = one-time essential costs + (monthly income gap × buffer months)

funding gap = max(0, target - current emergency savings)

When the monthly income gap is positive:

current coverage = max(0, current savings - one-time costs) ÷ monthly income gap

When the monthly income gap is zero, current coverage is not applicable because there is no monthly shortfall to divide into the remaining savings.

When the funding gap is zero, months to target is 0. When a funding gap remains and the monthly contribution is positive:

months to target = funding gap ÷ monthly contribution, rounded up

The calculator shows that timeline only when it is within its 1,200-month projection limit. A longer result is reported as beyond the supported projection rather than as a precise completion date.

Amounts are rounded to two decimal places. Contributions are treated as arriving at the end of each month. The estimate excludes savings interest, tax, fees, withdrawals, and changes in expenses. If an account's displayed rate is affecting how you read the result, see how high-yield savings accounts work. A contribution of zero produces no finite timeline when a funding gap remains.

The buffer can be from 0 to 24 months. A zero-month scenario can help isolate the current balance, but it is not a recommendation to keep no emergency savings.

Worked example

Morgan and Sam count 2,600 of essential monthly costs. They test what happens if Morgan's income stops while Sam's dependable 1,400 continues. They add a possible 900 urgent travel and care cost, choose a 4.5-month buffer, have 3,200 saved, and plan to add 425 a month.

Monthly gap        max(0, 2,600 - 1,400) = 1,200
Target             900 + (1,200 × 4.5) = 6,300
Funding gap        6,300 - 3,200 = 3,100
Current coverage   (3,200 - 900) ÷ 1,200 = 1.92 months
Timeline           3,100 ÷ 425, rounded up = 8 months

With those inputs, the calculator reports a monthly income gap of 1,200, a target of 6,300, a funding gap of 3,100, 1.92 months of coverage after the one-time cost, and 8 months to the target.

Then they run the reverse case, keeping Morgan's income and removing Sam's. The target falls because more dependable income remains. They keep both saved scenarios in their notes rather than blending them into a fictional average interruption.

Read the result as a range, not a grade

A target can be useful even when it is far away. It gives the next contribution a job. It can also be split into stages, such as one expensive surprise, one month of essential costs, and the longer buffer you eventually want.

Ask each other:

  • Which cost would continue even if one income stopped?
  • Which cost could fall, and how quickly?
  • Would either person need separate access to some of this money?
  • What would make us change the buffer or contribution?

If the result seems unreachable, change the timing before erasing real needs from the expense total. A staged target can make the first useful amount visible without pretending it covers the full scenario.

What the estimate cannot promise

The calculator does not predict job-search time, which income will continue, one-time costs, inflation, account access, or whether a particular savings product is suitable. It calculates the scenario entered. It cannot tell you which costs are legally required or which balance has protection under local deposit rules.

Run the cases separately and keep the one that matches the interruption you are actually preparing for.