Early Retirement Calculator
Estimates the age at which you can retire early using the FIRE (Financial Independence, Retire Early) framework. Useful for anyone targeting financial independence and wanting a concrete retirement age target.
About this calculator
The FIRE method targets a savings goal equal to 25 times your annual expenses — known as your FIRE number — based on the 4% safe withdrawal rule. This calculator uses the formula: retirementAge = currentAge + log((annualExpenses × 25) / currentSavings) / log(1.07). The log ratio measures how many years it takes for your current savings to grow to your FIRE number at an assumed 7% real annual return. The constant 25 comes from the inverse of the 4% rule (1 / 0.04 = 25). Note that this formula uses only current savings for the projection and does not factor in ongoing annual savings contributions; it answers 'how long until current savings alone reach the FIRE number.' For a more complete picture, also input your annual savings.
How to use
Suppose you are 32 years old, spend $45,000 per year, and currently have $80,000 saved. Step 1 — FIRE number: $45,000 × 25 = $1,125,000. Step 2 — Ratio: $1,125,000 / $80,000 = 14.0625. Step 3 — log(14.0625) / log(1.07) = 2.644 / 0.02938 = 37.97 years. Step 4 — Retirement age: 32 + 37.97 ≈ age 70. This result suggests you'd need to significantly increase savings or reduce expenses to achieve early retirement.
Frequently asked questions
How does the FIRE calculator estimate early retirement age?
The calculator finds how many years your current savings need to grow — at a 7% real annual return — to reach your FIRE number (annual expenses × 25). It uses logarithms to solve the compound growth equation for time: years = log(FIRE number / current savings) / log(1.07). Adding that to your current age gives your projected retirement age. The result is most accurate when your savings are already substantial; if you're still in early accumulation, your annual savings rate is the bigger driver.
What is the FIRE number and how do I calculate it for early retirement?
Your FIRE number is the total investment portfolio needed to sustain your lifestyle indefinitely without working. It equals your annual expenses multiplied by 25, which is derived from the 4% safe withdrawal rule (1 / 4% = 25). For example, if you spend $50,000 per year, your FIRE number is $1,250,000. Once your portfolio reaches this threshold and earns an average 7% return, it should theoretically generate enough to cover your expenses in perpetuity, assuming historically typical market performance.
Why does the early retirement calculator use a 7% return assumption?
The 7% figure represents the approximate inflation-adjusted (real) long-term return of a diversified stock market index fund, based on historical U.S. market data. Using a real return rather than a nominal return keeps your spending target in today's dollars, making the result more intuitive. Some FIRE planners use 6% to be conservative or 8% for optimistic scenarios. Changing the assumed return significantly affects the projected retirement age, so it is worth stress-testing your plan at multiple return rates.