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FIRE Calculator

Find your financial independence number, see how many years until you can retire early, and track your progress year by year.

Your age right now. This is your starting line.

Everything you've already invested toward retirement.

What you invest each month. Annual contribution is this × 12.

Safe withdrawal rate (SWR) is the share of your portfolio you draw down each year. 4% is the classic Trinity-study guideline; go lower for more cushion.

Long-run stock returns run about 7–10%. Enter a nominal rate; inflation is handled separately below.

How fast prices climb. The US long-run average is about 2.5–3%.

Off by default: once you hit your FI number, contributions stop and the portfolio coasts on returns alone. Check it to keep investing all the way to age 100.

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How We Calculate This

FI Number (your portfolio target)

Your FI Number is the portfolio size needed so that withdrawing a safe percentage each year covers your annual retirement spending:

FI Number = Monthly Spending × 12 ÷ Safe Withdrawal Rate

With a 4% safe withdrawal rate and $4,000/month spending, that's $4,000 × 12 ÷ 0.04 = $1,200,000, the classic "25× rule." You can adjust the withdrawal rate to reflect your personal risk tolerance.

Nominal model with monthly compounding

All projections are in nominal dollars and computed month by month. Each month your portfolio grows at the monthly expected return and your monthly savings is added at month-end:

balance = balance × (1 + expectedReturn/12) + monthlySavings

The FI Target grows every month with inflation:

FI Targetm = FI Number × (1 + inflationRate/12)m

FIRE is reached the first month your portfolio meets or exceeds that month's FI Target. The projection always runs to age 100. The year-by-year table shows 12-month snapshots of this monthly model, which is why the table may differ slightly from annual-model approximations. The expected return is used as a nominal rate; inflation enters the model only through the growing FI Target.

Keep investing after FI?

By default this calculator assumes you stop adding new contributions once you reach your FI number. After that crossover month, the portfolio keeps compounding on returns alone, which is why it still grows post-FI even without new savings.

Check Keep investing after FI? to model continuing to save and invest all the way to age 100. Either way, your FI Number, FI age, and crossover year do not change. Only the post-FI portfolio path and the Contributions chart line change.

Derived savings rate and current progress

Your savings rate is derived from your inputs. It is never entered directly:

Savings Rate = Monthly Savings ÷ (Monthly Savings + Monthly Spending)

This is the single biggest lever on your FIRE timeline. It simultaneously grows your contributions and (if paired with lower spending) shrinks the FI Number you need to reach. Current progress is simply your current savings divided by your FI Number.

Your retirement paycheck

Your retirement paycheck confirms that the FI Number is internally consistent: withdrawing SWR% of the FI Number each year equals exactly your annual retirement spending. This is true by construction: the FI Number formula is designed so that the annual withdrawal at SWR% covers your target spending precisely.

FIRE Calculator Formula

Your FI Number is the portfolio size needed so that a safe annual withdrawal covers your retirement spending:

FI Number = Monthly Spending × 12 ÷ Safe Withdrawal Rate

where Monthly Spending is your expected monthly expenditure in retirement, and Safe Withdrawal Rate is expressed as a decimal (e.g., 0.04 for 4%).

How to Use This Calculator

  1. Enter your Current Age and Current Savings / Investments.
  2. Enter your Monthly Savings / Investment, the amount you invest each month.
  3. Enter your Monthly Spending in Retirement, what you expect to spend per month when retired.
  4. Enter your Safe Withdrawal Rate (4% is the classic guideline from the Trinity Study).
  5. Enter your Expected Annual Return and Inflation Rate to model portfolio growth and the moving FI Target.
  6. Optionally check Keep investing after FI? to keep contributing past your FI date (off by default: contributions stop once you reach FI).
  7. Click Calculate to see your FI Number, years to FIRE, a FIRE Timeline chart, and a year-by-year projection (defaulting to 10 years past your FI date, expandable to age 100).

Frequently Asked Questions

What is FIRE (Financial Independence, Retire Early)?

FIRE is a movement focused on saving and investing aggressively so that investment income can cover your living expenses, letting you retire decades earlier than traditional retirement age. Financial independence is reached when your portfolio is large enough to sustainably fund your lifestyle. See how compound growth gets you there with the Compound Interest Calculator.

What is a FIRE number?

Your FIRE number is the size of the portfolio you need so that withdrawing a safe percentage each year covers your annual retirement spending. With a 4% safe withdrawal rate, your FIRE number is your annual retirement spending multiplied by 25. At $4,000/month ($48,000/year) that is $1.2 million.

What is the 4% rule?

The 4% rule is a guideline suggesting you can withdraw 4% of your portfolio in the first year of retirement, then adjust for inflation, with a high probability your money lasts 30+ years. It comes from the Trinity Study (Cooley, Hubbard, and Walz, 1998). This calculator lets you set any safe withdrawal rate.

Why does the FI target grow over time in the table?

The projection is shown in nominal dollars, so the FI target rises with inflation (compounded monthly) while your portfolio compounds monthly at your expected return. You reach FIRE the first month your portfolio catches up to that month's inflation-adjusted target; the table shows the year-end snapshots of this monthly model.

How is my savings rate calculated?

Your savings rate is your monthly savings divided by your total monthly cash flow (savings + retirement spending). It is the single biggest lever on your timeline. Raising it both grows your contributions and, paired with lower spending, shrinks the FI number you need.

How does my savings rate change how long I have to work?

There is a famous relationship: the higher your savings rate, the fewer working years you need. A 33% savings rate implies roughly 28 working years from scratch; pushing to 50% drops it to about 17. You can see the impact for your exact numbers in the YEARS TO FIRE tile and the year-by-year projection above.

What if I never reach FIRE by age 100?

If your inputs do not reach the FI target by age 100, the calculator tells you so and still shows your projected growth. Try raising your monthly savings, lowering your retirement spending, or assuming a higher return. To see how a balance grows over the long run, use the Compound Interest Calculator.

Why does my portfolio keep growing after I reach FIRE?

Even after you hit your FI number, your invested balance keeps earning returns, so it continues to compound. By default this calculator assumes you stop adding new contributions once you reach FI (you've retired), so the post-FI growth comes from returns alone. If you'd rather model continuing to invest past your FI date, check "Keep investing after FI?" and the projection will keep adding your monthly savings all the way to age 100. Either way, your FI number and FI age don't change. Only the path after FI does.

Does this account for taxes or different account types?

This version models a single portfolio with one return rate and one withdrawal rate. It does not break out pre-tax, post-tax, or Roth accounts, or model variants like Coast, Lean, or Barista FIRE. To build toward a specific savings target, use the Savings Goal Calculator.

Glossary: key terms used on this page

  • FIRE: Financial Independence, Retire Early. A strategy of aggressive saving and investing so your portfolio can fund your living expenses indefinitely, letting you stop working years or decades before the traditional retirement age.
  • FI: Financial Independence. The point at which your investment portfolio is large enough to cover your spending through safe withdrawals. "FI" and "FIRE" are often used interchangeably, though FI emphasizes the milestone and FIRE emphasizes the lifestyle choice.
  • SWR: Safe Withdrawal Rate. The percentage of your portfolio you withdraw each year in retirement. The classic guideline is 4%, from the Trinity Study, which found a 4% initial withdrawal (adjusted for inflation) historically sustained a portfolio for 30+ years.
  • FI Number: the portfolio size you need so that withdrawing at your chosen SWR covers your annual spending (e.g., $48,000/yr spending ÷ 0.04 SWR = $1,200,000).

Further Reading

Related Calculators

Savings Goal Calculator

Calculate how much you need to save each month to reach your financial goal on time.

Barista FIRE Calculator

Most Barista FIRE calculators make you guess a semi-retirement age. This one finds it for you. Enter your numbers and see exactly when part-time income plus your portfolio cover your spending.

Retirement Drawdown Calculator

Will your money last? Enter your portfolio, planned withdrawals, and any pension or other income to see exactly how long your retirement savings hold out.