FIRE Calculator — Frequently Asked Questions

What exactly does this calculator compute?

It computes your FIRE number (25× your annual spending) and then compounds your current savings plus yearly contributions until the portfolio reaches that target, reporting the age and year you get there.

Where does the 25× number come from?

It is the inverse of the 4% safe withdrawal rate. If you withdraw 4% of your portfolio per year, the portfolio must be 25 times one year of spending to sustain that withdrawal.

What return should I enter?

A broad stock index has returned about 7% per year after inflation over the long run. Enter a conservative figure you can live with; the calculator shows how sensitive your timeline is.

What if my spending changes in retirement?

Enter your expected retirement spending, not your current spending. Many people spend less once they stop commuting and more on travel — estimate honestly.

How do I account for inflation?

Either bump your spending up by ~2% a year in your head, or use a slightly lower withdrawal rate. The calculator works in today’s dollars at the return you enter.

Is the 4% rule safe?

The Trinity study found a 4% initial withdrawal (rising with inflation) survived most 30-year historical periods. Longer retirements and bad start years carry more risk, so some use 3.5%.

What is the difference between Lean, Fat, and Barista FIRE?

Lean uses a small budget, Fat a large one, and Barista pairs a smaller portfolio with part-time income. All use the same 25× math with different spending or income inputs.

Can I include my house in the FIRE number?

You can count net home equity as net worth, but you usually cannot spend it without selling or borrowing. The "with real estate" tool shows both views side by side.

My pension or Social Security covers part of my costs — now what?

Subtract that guaranteed income from your spending before multiplying by 25. The "with pension" tool does this automatically.

Why does starting earlier matter so much?

Compound growth accelerates with time. Money invested at 25 has roughly 15 more years of growth than money invested at 40, often more than doubling the final amount.

What if I am already past my FIRE number?

The calculator tells you when your savings already meet or exceed the target, meaning you are financially independent today.

Is any of this financial advice?

No. This is an educational illustration using standard formulas. Real plans depend on your taxes, health, and tolerance for market swings — talk to a fiduciary advisor for your situation.