Choosing a horizon
Three, six and twelve months are scenarios—not laws.
Income stability, dependants, multiple earners, insurance, essential fixed costs and access to other resources can all change how a reserve horizon is interpreted.
Personal finance calculator
Model a cash-reserve target from essential monthly expenses and the number of months you choose. The calculator shows the arithmetic; it does not prescribe one correct reserve.
—
Target reserve = essential monthly expenses × user-selected months. Time to target divides any funding gap by the monthly amount added and rounds up to the next whole month.
No interest, inflation, taxes, withdrawals or changing expenses are modeled. The result is an arithmetic planning scenario, not financial advice.
Formula
A household with €1,500 of essential monthly expenses would model €4,500 at three months, €9,000 at six months and €18,000 at twelve months.
essential monthly expenses × target monthscurrent savings ÷ essential monthly expensesmax(0, target − current savings)ceil(funding gap ÷ monthly amount added)Choosing a horizon
Income stability, dependants, multiple earners, insurance, essential fixed costs and access to other resources can all change how a reserve horizon is interpreted.
Source
Consumer Financial Protection Bureau — An essential guide to building an emergency fund