How the Coast FIRE Retirement Calculator Works
Coast FIRE means you've saved enough early in life that, with no further contributions, your investments will grow to your full FIRE number by retirement age. This calculator determines the lump sum you need today to "coast" to financial independence.
FIRE Number = Annual Retirement Expenses / Safe Withdrawal Rate
Coast FIRE Target = FIRE Number / (1 + r - inflation)n where n = years until retirement, r = expected return.
Example: $50k annual expenses, 4% SWR → FIRE number = $1,250,000. With 25 years to retirement and 7% return (2.5% inflation → real return ~4.4%), Coast FIRE target = $1.25M / (1.044)25 ≈ $429,000.