Comprehensive Guide
Learn more in our Personal Finance Guide.
How it works
FIRE — financial independence, retire early — reduces retirement to one number: the invested sum from which you can draw your annual spending indefinitely. The calculator builds it from the safe withdrawal rate. At the classic 4% rule, the number is annual spending times 25; at a more cautious 3.5%, times 28.6. It then projects your current savings forward, adding your monthly contributions and compounding at your return rate, and finds the year the balance crosses the target. Two levers move the date, and they are not equal. Raising contributions grows the pile faster, but cutting spending works twice — it shrinks the FIRE number itself while freeing more to invest, which is why savings rate predicts the date better than income does. A household spending $48,000 needs $1.2 million at the 4% rule; spending $40,000 needs only $1 million, and the $8,000 a year not spent accelerates the journey further. Treat the result as a planning figure, not a promise — returns vary, the 4% rule is a historical backtest, and a long retirement argues for the more conservative withdrawal rate.Formula
FIRE number = annual spending / withdrawal rate | then compound savings + contributions until balance >= target
Tips
- Cutting spending helps twice — it shrinks the target and frees more to invest.
- The 4% rule is a historical backtest, not a guarantee; 3.5% is the cautious choice.
- Use 7% for an inflation-adjusted answer in today's purchasing power.
- Savings rate predicts the date better than income does.
- Recheck yearly — a strong market year can pull the date forward by several more.
Frequently asked questions
What is my FIRE number?
Your annual retirement spending divided by your safe withdrawal rate. At the classic 4% rule it is spending times 25 — $48,000 a year needs $1.2 million invested. At a more conservative 3.5% it is times 28.6. That is the sum from which you can draw spending indefinitely.
Is the 4% rule safe?
It is a historical backtest — a portfolio that survived every 30-year stretch in US market history — not a promise. For retirements longer than 30 years or low future returns, many planners prefer 3.5%. It is a sound planning anchor, not a law of nature.
How is years to FIRE calculated?
The calculator compounds your current savings and monthly contributions at your return rate, year by year, until the balance reaches your FIRE number. The count of years is the answer. Higher contributions or returns shorten it; a higher FIRE number lengthens it.
Does cutting spending really help more than earning more?
Often, yes — because it works on both sides. Spending $8,000 less per year shrinks your FIRE number by $200,000 at the 4% rule and simultaneously frees $8,000 a year to invest. A raise only adds to contributions, and only if lifestyle does not absorb it first.
What return rate should I assume?
About 7% for a diversified stock portfolio after inflation, which keeps the answer in today's purchasing power, or 10% nominal. For a balanced portfolio with bonds, 5-6% is the more prudent assumption. The result is a plan, so treat the rate as an estimate.