FIRE Number Calculator

Your FIRE number is annual expenses divided by your safe withdrawal rate; at 4% it is 25 times yearly spending.

Quick answer

Your FIRE number is annual expenses divided by your safe withdrawal rate; at 4% it is 25 times yearly spending. With the default inputs (Annual expenses $48,000, Withdrawal rate 4%, Current savings $150,000, Monthly investment $1,500, Annual return 6%) the result is FIRE number $1,200,000, Gap $1,050,000, Time to FIRE 20y 2m.

Method

FIRE number = annual expenses / (withdrawal rate / 100). Gap = FIRE number - current savings (never below zero).

Time to FIRE compounds your current savings monthly at the annual return and adds the monthly investment until the balance reaches the FIRE number, up to 100 years.

Worked example

Annual expenses	$48,000
Withdrawal rate	4%
Current savings	$150,000
Monthly investment	$1,500
Annual return	6%
FIRE number	$1,200,000
Gap	$1,050,000
Time to FIRE	20y 2m

Assumptions and limits

The withdrawal rate is an assumption, not a guarantee; the often-cited 4% rule comes from historical US data and does not suit every horizon.
Constant returns, no inflation adjustment and no taxes are modelled.

Educational estimate only. It is not financial, tax, legal, or investment advice.

FAQ

How do I calculate my FIRE number?

Divide annual expenses by the withdrawal rate. With the defaults ($48,000 expenses at 4%%) the FIRE number is $1,200,000.

What is the 4% rule?

A guideline that a portfolio can fund about 4% of its initial value per year; it equals a target of 25 times annual spending. It is a historical rule of thumb, not a guarantee.

How long until I reach FIRE?

The calculator compounds your savings plus monthly investment until the balance reaches the target. With the defaults it is 20y 2m.

What is the gap?

The FIRE number minus your current savings. With the defaults it is $1,050,000.

Is my data stored?

No. The calculation runs in your browser and the inputs are not sent to or saved by this site.