Emergency Fund Calculator: How Much Should You Save?

Calculate your emergency fund from essential monthly expenses and the months you want covered. See how long your monthly savings will take.

Last updated: October 3, 2026

Example: the calculation with the default values

The defaults are example values, not an average. Enter your own numbers and press “Calculate” to run it with yours.

Already there

Still missing

$4,500

Your cushion covers

0.0 days

What keeps running per month	$1,500
Months it should cover	3.00
Your target	$4,500
Already there	$0
Still missing	$4,500

Assumptions behind this calculation

This counts what keeps running, not what you earn. An emergency fund carries expenses; it does not replace an income – which is why the number is smaller than the one you have heard.
Months the cushion should carry: 3
Three months is a common rule of thumb, not a measured figure. Insecure work needs more; very secure work needs less.
Calculated without interest to simplify the plan. Actual interest and access depend on the account you choose.

How we calculate

Your target is your essential monthly costs times the months the cushion should cover. What you already have comes off; the rest is missing.

With a monthly saving, the missing amount divided by it and rounded up is the number of months to your target. No interest is counted.

How long your cushion lasts today is what you have divided by your monthly costs, times 30.4 days per month.

The reasoning behind these numbers, with sources, is in the article: Emergency Fund: How Much to Save and Where to Keep It.

Frequently asked

How big should an emergency fund be?

The calculator takes your essential monthly costs times the months the cushion should cover. With the defaults – $1,500 a month, 3 months – that is $4,500. Three months is a common rule of thumb, not a measured figure. Insecure work needs more; very secure work needs less.

Why does it use expenses and not salary?

This counts what keeps running, not what you earn. An emergency fund carries expenses; it does not replace an income – which is why the number is smaller than the one you have heard.

How long will it take to build my emergency fund?

The missing amount divided by your monthly saving, rounded up. In the defaults the monthly saving is zero, so the example names no number of months – enter yours and it appears.