FIRE & Early Retirement Calculator

Your FIRE number, in one division

Financial independence has a deceptively simple definition: the day your invested assets can fund your life without a paycheck. Because a diversified portfolio can safely shed a small slice of itself every year, the whole question collapses into a single division.

Spend $40,000 a year at a 4% withdrawal rate and your number is $1,000,000. Demand a margin of safety at 3.25% and the same lifestyle costs roughly $1.23 million; gamble on 5% and you can stop near $800,000 - with a thinner cushion if markets fall early in retirement. The slider exists because the right rate is a judgement about how many decades your money must last, not a law of physics.

How the growth simulation works

This simulator compounds monthly rather than annually, which mirrors how contributions actually land in a brokerage account - and how market growth snowballs on top of itself.

A 7% nominal return works out to roughly 0.565% per month, applied to the entire running balance. Meanwhile the finish line refuses to sit still: at 2.5% inflation, a $1 million goal becomes about $1.4 million for a 30-year-old planning to retire at 55. On the chart above, the gold dashed line is that moving target and the black line is your projected portfolio - you are financially independent the month the two first touch, which the “Years to FI” tile reports to the month.

Run your own simulation

1. Set your current age and target retirement age - the horizon drives every other number.
2. Enter invested savings and a realistic average monthly contribution, bonuses included.
3. Choose an expected annual return; 7% is a defensible long-run nominal figure for globally diversified equities.
4. Enter retirement spending in today’s dollars, then pick a safe withdrawal rate - 4% is the classic default.
5. Read the FIRE number, years-to-FI and surplus tiles, then stress-test by shaving a point off the return and adding one to inflation.

Lean FIRE, fat FIRE and coasting

FIRE is less a single destination than a family of milestones, each with its own arithmetic:

• Lean FIRE - covering a minimal budget, often $25,000-$40,000 a year, prioritizing freedom over comfort.
• Fat FIRE - retiring on a padded budget that funds travel, hobbies and generosity: the same formula with a bigger numerator.
• Coast FIRE - the checkpoint where existing savings, left untouched, compound into your full number by retirement age. The “Coast FI number” tile above marks it: below that balance, keep contributing; above it, you only need income that covers today’s bills.
• Barista FIRE - the hybrid stage where part-time or low-stress work pays current bills while the portfolio keeps compounding toward the full number.

Compounding is only half of personal finance - the other half is what you earn and what you owe. Pair this page with the freelance rate calculator to price your hours properly, or with the loan payoff calculator to see how retiring an 18% APR debt outruns a 7% market return.