How this calculator works
Financial independence — the "FI" in FIRE — happens when your investments are large enough that the income they throw off covers your living costs without you working. The whole idea collapses into a single target called your FIRE number: your annual spending divided by a safe withdrawal rate. At the widely-used 4% rate, that's 25 times your yearly expenses. Spend $50,000 a year, and roughly $1.25 million invested means work becomes optional.
This tool finds that number, then projects how your current savings plus monthly contributions grow toward it, and tells you the age you'd reach it. Everything is calculated in today's dollars — it converts your investment return and inflation into a real, after-inflation growth rate — so the target and your projected balance are directly comparable, with no inflation sleight of hand.
The method
The target comes straight from the withdrawal rate; growth uses a real return so inflation is already handled:
It marks the month your balance first reaches the target, and computes your Coast FIRE number — the amount that would grow to the target by age 65 with no further saving.
- FIRE number: spending ÷ 4% =
$1.25 million(25×). - Real return: about
3.9%after inflation. - Reach it in ~25 years — financial independence around
age 60, starting from 8% of the way there. - Coast FIRE: your Coast number is roughly
$400,000— hit that and you could stop saving and still retire at 65 on growth alone.
Acronyms used on this page
- FIRE
- Financial Independence, Retire Early
- FI
- Financial Independence
The levers that actually matter
FIRE math has a counter-intuitive truth: your savings rate matters more than your salary or your investment returns, because it does double duty — every dollar saved is both a dollar invested and a dollar you've shown you can live without, which lowers the target itself. Cutting annual spending by $5,000 doesn't just free up cash to invest; it shrinks your FIRE number by $125,000 at a 4% rate. That's why frugality and income both accelerate the date, and why two people earning the same can retire decades apart. The withdrawal rate is the other big dial — a more conservative 3.5% rate is safer for very long retirements but raises the target meaningfully.
Frequently asked questions
How much do I need to retire?
About 25× your annual spending at a 4% withdrawal rate — $1.25M for $50k/year of spending. The exact figure depends on your withdrawal rate, horizon, and other income like Social Security.
What is the FIRE number?
The invested amount that lets you live off withdrawals indefinitely: annual expenses ÷ safe withdrawal rate. At 4%, that's 25× yearly spending.
What is Coast FIRE?
The point where your invested savings would grow to your full target by retirement age with no more contributions. After it, you only need to cover current expenses — retirement is already funded by compounding.
Is the 4% rule guaranteed?
No — it's a historical guideline, safest for ~30-year retirements. Very early retirees often use 3.25–3.5% for a longer horizon. Pair this with a drawdown analysis to test how long the money actually lasts.