The 4% rule, explained
Why this withdrawal rate became the FIRE community standard — and its limits.
Ask anyone in the FIRE (Financial Independence, Retire Early) community how big a corpus they need, and you’ll almost always get the same shortcut back: multiply your annual expenses by 25. That number isn’t arbitrary — it falls directly out of a single assumption called the 4% rule, and it’s worth understanding where it actually comes from before leaning on it for a decision this size.
Where the number comes from
The 4% rule traces back to research (most famously the “Trinity Study”) that tested how often a retirement portfolio, invested in a mix of stocks and bonds, would have survived a 30-year retirement while withdrawing a fixed percentage of the starting corpus each year, adjusted for inflation. A 4% starting withdrawal rate held up across most historical 30-year periods without the corpus running out — not a guarantee, but a track record good enough to become the default starting assumption.
The rule converts directly into a target corpus: if you can safely withdraw 4% of your corpus a year, then your corpus needs to be your annual expenses divided by 4% — which is the same as multiplying annual expenses by 25.
The 25x shortcut
₹60,000 a month in expenses is ₹7,20,000 a year. Using the real formula the FIRE Calculator runs (requiredCorpus = annualExpense / swr), a 4% safe withdrawal rate means a required corpus of ₹7,20,000 ÷ 0.04 = ₹1,80,00,000— exactly 25x the annual expense, confirming the shortcut isn’t an approximation, it’s the same formula rearranged.
Find the age you could financially retire based on your savings rate.
The withdrawal rate you assume moves the target corpus a lot, because it’s in the denominator — small changes in the rate produce large changes in how much you need to save.
| Assumed safe withdrawal rate | Corpus needed | Multiple of annual expenses |
|---|---|---|
| 5% | ₹1,44,00,000 | 20x |
| 4% | ₹1,80,00,000 | 25x |
| 3.5% | ₹2,05,71,429 | 28.6x |
| 3% | ₹2,40,00,000 | 33.3x |
Dropping the assumption from 4% to 3.5% — a change many FIRE planners make deliberately, for reasons covered next — raises the required corpus by over ₹25 lakh on the same ₹60,000/month expense figure, with nothing else about the plan changing.
When it stops being a safe assumption
The original research was built around a 30-year retirement horizon. FIRE, by definition, often means retiring decades earlier than a conventional retirement age — a 35-year-old retiring early could easily need the corpus to last 50-60 years, not 30. Many FIRE planners deliberately use a more conservative 3-3.5% withdrawal rate specifically to compensate for that much longer horizon.
The rule also assumes a specific historical mix of stock and bond returns, and says nothing about the order those returns actually arrive in — a portfolio that has to withdraw money during an early market downturn can fail even at a rate that looks safe on paper, purely because of when the bad years happened to land. See sequence-of-returns risk for that related but distinct problem.
Find the age you could financially retire based on your savings rate.
Work out the corpus you'll need to retire at your chosen age.
All figures are indicative and for educational purposes only — not financial advice.
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