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Use the Emergency Fund Calculator
The calculator gives the first number. The worksheet turns that number into a comparison you can revisit.
How much emergency fund do I need?
Use expenses, target months, current savings and monthly contributions to plan a practical emergency fund target.
Start with the job, not the rule of thumb
An emergency fund is not a magic number. It is a cushion for a specific job: keeping essential bills paid when income drops, a car repair lands, a boiler breaks, a pet needs care or a short gap between jobs appears. That is why the calculator starts with essential monthly expenses instead of total lifestyle spending.
The common rule of thumb is to think in months of expenses, but the useful version is more personal: what must keep being paid if income is disrupted, and how long would you want that cover to last? A single person with stable income may choose a different target from a household with dependants, variable income or a large rent payment.
What to put into the calculator
Use the monthly amount needed for housing, utilities, food, transport, insurance, minimum debt payments and essential communication. Optional meals out, shopping, entertainment and holidays are usually not emergency baseline costs. Then choose a target number of months, enter current savings and add a monthly contribution you can actually repeat.
Where estimates can mislead
The result can look too easy if the monthly contribution is unrealistic. It can also look too precise if your essential expenses are guessed. If rent, energy or insurance renewals are changing soon, run a second version with the higher number.
Make the answer useful
Print the worksheet, write the target fund at the top and then list the expenses included. If the gap is large, do not treat that as failure. Split it into a first milestone, such as one month of essentials, then the longer target.