Financial
Calculate Coast FI number: invested balance needed to coast to retirement
Divide annual retirement spending by a chosen withdrawal-rate assumption and discount back to today using PV or (1 + RealReturn)^Years.
Full FI target vs Coast FI milestone
Full Financial Independence (FI) equals AnnualSpending / AssumedWithdrawalRate (e.g., 48,000 / 0.04 = 1,200,000).
Coast FI discounts the assumed future target using a constant real (inflation-adjusted) return. Under those assumptions only, this starting balance grows to the target without new contributions. Actual returns do not follow a fixed path.
| AnnualSpend (A) | SWR (B) | RealReturn (C) | Years (D) | Coast FI Target |
|---|---|---|---|---|
| 48000 | 0.04 | 0.07 | 25 | 1,200,000 / 1.07^25 = 221,099 |
Coast FI formula (algebraic and PV forms)
Both (A2 / B2) / (1 + C2)^D2 and PV(C2, D2, 0, -(A2 / B2)) return 221,099.
=ROUND((A2 / B2) / (1 + C2)^D2, 0)Check Coast FI milestone status
Compare current invested assets (E2) against the discounted Coast FI threshold.
=IF(E2 >= (A2 / B2) / (1 + C2)^D2, "Scenario threshold reached", "Saving")Inputs and interpretation
The 4% withdrawal and 7% real-return inputs are illustrative assumptions, not safe or guaranteed rates. Keep spending in today’s purchasing power when using a real return. Require a positive withdrawal rate, real return greater than -100%, and nonnegative years. This simplified model omits return variability, retirement duration, fees, taxes and sequence-of-returns risk. Crossing its threshold does not establish that it is safe to stop saving.
Try the example
Use the original values or change them to test your understanding.