FIRE Number Calculator

Estimate your "FIRE number" — the portfolio size commonly used as a financial independence target — from your annual expenses and a chosen withdrawal rate. The classic 4% rule comes from historical (Trinity Study) research on sustainable withdrawal rates; this is an educational estimate, not financial advice.

Annual Expenses ($)

Withdrawal Rate (%)

How the target is worked out

The calculator divides your spending by the withdrawal rate you choose, and shows the same answer as a multiple of one year's expenses:

FIRE number      = annual expenses / (withdrawal rate / 100)
expense multiple = 100 / withdrawal rate

At the default $40,000 and 4%, that is 40000 / 0.04 = $1,000,000, shown as 25.0×. Drop the rate to 3.5% and the multiple becomes 100 / 3.5 = 28.6×, so the target rises to $1,142,857. Raise it to 5% and you need 20×, or $800,000.

Picking a rate, and what the 4% figure really is

The 4% rule and its 25× twin come from the Trinity study, which tested fixed inflation-adjusted withdrawals against historical US stock and bond returns over 30-year retirements. That is a historical success rate for that data and that horizon, not a guarantee.

Sequence-of-returns risk. Two retirements with the same average return can end differently. A crash in the first few years, while you are selling to fund spending, does far more damage than the same crash at year 25.
These are today's dollars. Enter what you spend now and the target comes back in today's money, not the nominal sum you will see on a statement decades from now.
Longer than 30 years? Retiring at 40 means planning for 50-plus, which is why many early retirees use 3% to 3.5% instead.

Tax and health cover have to sit inside the expenses figure, since the portfolio funds them. How withdrawals are taxed depends on your account types and country.

Frequently asked questions

How much do I need to retire on $40,000 a year?

$1,000,000 at a 4% withdrawal rate, or $1,142,857 at 3.5%. Divide your annual spending by the rate as a decimal.

Is the 4% rule still safe?

It is a historical result, not a promise. The Trinity study found that rate survived 30-year retirements in past US market data; a longer horizon, a different mix of assets or a bad first decade can change the answer.

Why does the tool show 25×?

Because 100 / 4 = 25, so a 4% rate and a 25-times-expenses target are the same statement. At 3% it shows 33.3×, and at 5% it shows 20.0×.