Set a spending goal before a FIRE label
Fat FIRE describes a financial-independence goal with relatively high planned spending. Lean, regular and Fat FIRE are informal labels, not official income bands. Housing, healthcare, location, family needs and taxes affect what the same dollar budget can support.
This calculator estimates an accumulation target and a path toward it. It does not establish that investment returns will pay expenses indefinitely. A first crossing is only a threshold event under the entered assumptions.
Keep the units and timing consistent
- Enter investable assets available to support the plan. A home or illiquid business is not automatically cash available for portfolio withdrawals. Liabilities and access restrictions need separate treatment.
- Use a real, after-inflation effective annual return. Use starting-date purchasing power for spending and contributions. There is no separate inflation calculation, so mixing a nominal return with today's fixed spending target would distort the result.
- Choose an amount per contribution, its frequency, and growth above inflation. Deposits occur at the end of the selected month, quarter or projection year. Growth begins after a complete 1-, 2- or 5-year interval.
- Enter spending that this portfolio must fund and an initial withdrawal-rate assumption. Account for taxes, other income, and expenses outside the portfolio model separately.
- Compare the first crossing with the annual schedule. Projection year 1 is the first 12 months, not the remaining part of the current calendar year. Ages refer to the end of each projection year.
The target is arithmetic, not a guarantee
Portfolio target = annual spending / (withdrawal rate / 100). With hypothetical annual spending of $200,000, a 4% assumption gives $5 million; 3% gives about $6.67 million. These alternatives show sensitivity to the rate. They do not establish that either rate is appropriate.
The familiar 4% rule describes a first-year withdrawal based on the initial retirement portfolio, followed by inflation adjustments to that dollar amount. It is not the same as taking 4% of each year's remaining balance. Historical withdrawal research depends on portfolio composition and retirement length; it cannot promise an unlimited spending horizon.
How the monthly projection works
The monthly return is (1 + annual real return)^(1/12) - 1. Each month the starting balance earns that constant return, then the scheduled contribution is added. With a hypothetical $100,000 starting balance, 10% effective annual return and no contributions, the balance after 12 months is $110,000.
A hypothetical $2,000 monthly contribution with 10% annual growth contributes $24,000 in projection year 1 and $26,400 in year 2. Ten percent growth every two years leaves the contribution unchanged for 24 months before the first increase. These are contribution assumptions, not forecasts of salary growth.
The model checks whether current assets already meet the target, then checks each monthly balance for up to 600 months. A reported month is a modeled interval from the calculation date. It is not an exact retirement date; changing the assumptions or experiencing uneven returns can change the outcome.
Accumulation is not a withdrawal plan
The full 50-year schedule continues contributions and growth after the first crossing. It does not stop work-related saving, withdraw living expenses, test a retirement lifespan or include fees, taxes, healthcare shocks and benefit eligibility. Treat the totals as an accumulation scenario only.
The order of returns matters when money is added or withdrawn. Losses early in retirement can leave fewer assets available for a later recovery. A constant-rate projection omits that risk, so crossing the target is insufficient evidence that retirement spending is sustainable.
Further reading: Schwab on the 4% rule's assumptions and limits and Schwab on sequence-of-returns risk. These references explain the limitations; they do not endorse this calculator's default inputs. Reviewed October 21, 2026.