FIRE Calculator

FIRE stands for Financial Independence, Retire Early. Once your investment portfolio is large enough that a safe withdrawal (typically 4%) covers your annual expenses indefinitely, you have the freedom to stop working — whether you do or not is up to you.

The 4% rule comes from the 1998 Trinity Study, which found that retirees who withdrew 4% of a balanced stock/bond portfolio in year one — and adjusted that amount for inflation each year — almost never ran out of money over a 30-year retirement. It implies a target portfolio of 25× your annual expenses. (The original study tested S&P 500 stocks with long-term corporate bonds at 0/100, 25/75, 50/50, 75/25 and 100/0 mixes; the popular “60/40” label is a later simplification.)

Lean FIRE assumes a frugal post-retirement lifestyle (~60% of today's spend). Regular FIRE keeps your current lifestyle. Fat FIRE targets a premium, no-compromise lifestyle (~2× spend). The same income and savings rate hit Lean far sooner than Fat.

7% is the commonly cited inflation-adjusted (real) long-run return for the US S&P 500 with dividends reinvested. Because it's already real, you can interpret every dollar in the projection as today's purchasing power — no need to inflation-adjust separately.

FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate. At 4% SWR that's Annual Expenses × 25. At 3.5% it's roughly × 28.6; at 5% it's × 20.

We simulate your portfolio month by month: current savings grow at the return rate while monthly contributions are added. Years-to-FIRE is the first year the portfolio crosses your target. Required monthly is the contribution needed for the portfolio to land exactly on the target at your chosen retirement age.

No. The model treats every dollar as post-tax, both during accumulation (contributions) and withdrawal. If you save in tax-advantaged accounts (401(k), IRA, HSA, ISA, NPS), the effective tax drag is far lower — but you should still validate your target against your actual tax situation.