Purposeful FIRE🌊Retirement Cash Flow Forecast
Model how long your savings last when multiple income sources activate at different ages. Add Social Security, a pension, or part-time income — each starting and ending at a different age — and see how they change your net withdrawal burden year by year.
Your Numbers
Enter income sources that start (or end) at a specific age. Leave amount at $0 to exclude. These reduce your net withdrawal each year they're active.
Your Results
| Age | Base Withdrawal | Income Events | Net Withdrawal | Balance |
|---|---|---|---|---|
| 55 | $80,000 | +$0 | $80,000 | $1,510,000 |
| 57 | $84,872 | +$0 | $84,872 | $1,524,420 |
| 59 | $90,041 | +$0 | $90,041 | $1,530,134 |
| 61 | $95,524 | +$0 | $95,524 | $1,525,428 |
| 63 | $101,342 | +$0 | $101,342 | $1,508,336 |
| 65 | $107,513 | +$0 | $107,513 | $1,476,609 |
| 67 | $114,061 | +$24,000 | $90,061 | $1,451,674 |
| 69 | $121,007 | +$25,462 | $95,546 | $1,437,226 |
| 71 | $128,377 | +$27,012 | $101,364 | $1,409,187 |
| 73 | $136,195 | +$28,657 | $107,537 | $1,365,155 |
| 75 | $144,489 | +$30,402 | $114,086 | $1,302,393 |
| 77 | $153,288 | +$32,254 | $121,034 | $1,217,775 |
| 79 | $162,624 | +$34,218 | $128,405 | $1,107,741 |
| 81 | $172,527 | +$36,302 | $136,225 | $968,240 |
| 83 | $183,034 | +$38,513 | $144,521 | $794,662 |
| 85 | $194,181 | +$40,858 | $153,323 | $581,772 |
| 87 | $206,007 | +$43,347 | $162,660 | $323,621 |
| 89 | $218,552 | +$45,986 | $172,566 | $13,462 |
What Is Retirement Cash Flow Forecast?
Most retirement calculators ask a single question: how long does the money last given a fixed withdrawal amount? The Retirement Cash Flow Forecast asks a better question: how does the net withdrawal burden change over time as different income sources activate? An early retiree at 55 who has zero outside income today may have Social Security starting at 67, a small pension at 65, and a decade of part-time consulting work from 58 to 68. The actual net withdrawal in each of those phases is completely different, and a single-number projection misses all of that.
This calculator models up to three scheduled income events — each with a start age, an optional end age, and an annual income amount — layered on top of your base spending need. In each year, it sums the active event income, subtracts it from the base (inflation-adjusted) spending need, and that net figure is what actually draws down the portfolio. The result is a year-by-year view of both the net withdrawal and the portfolio balance, showing exactly when income events reduce your drawdown and by how much.
How This Calculator Works
Each year, base annual spending is inflation-adjusted. For each income event that is active (start age <= current age <= end age, or no end age), the event amount is also inflation-adjusted from its start year. The net withdrawal is the difference. The portfolio balance grows at the expected return before the net withdrawal is subtracted. The simulation stops at depletion or the maximum year count.
Personal Considerations
The most common retirement planning anxiety is a fixed-number fixation: 'I need $X to retire.' This calculator helps shift the framing toward a more dynamic picture where the withdrawal burden isn't constant but actually decreases over time as income sources activate. Someone with $1.2 million, spending $80,000/year, who receives $24,000 in Social Security at 67 and $18,000 from a pension at 65 has a very different picture than the same person with no income events. The raw 'years saved last' number obscures this completely.
The income event table is intentionally simple to encourage experimentation. Try adding a realistic part-time consulting income of $20,000/year from age 60 to 68 and watch how much it extends the projection. This makes visible what many FIRE planners know intuitively but rarely quantify: even modest side income in early retirement, not enough to live on, provides enormous value as a portfolio withdrawal reducer during the highest-risk early years.
If what you're feeling goes beyond what a calculator can help with, licensed clinicians are available at SanaNetwork.com, a referral network founded by this site's founder, Dr. Yoendry Torres.
Frequently Asked Questions
The Longevity Calculator uses a single fixed monthly withdrawal that stays constant (in inflation-adjusted terms). This calculator adds the ability to layer in multiple income events that start and stop at different ages, making the net withdrawal dynamic rather than fixed. If you have Social Security, a pension, or plan to do some part-time work, this calculator gives a more accurate picture.
Enter your full spending amount in 'annual spending.' Then enter SS, pension, and other income as income events. The calculator subtracts events from spending to get the net withdrawal, which is more transparent and lets you see the impact of each event separately.
The model assumes income events inflate at the same rate as expenses, which is a reasonable approximation for Social Security (which has COLAs) but not for a fixed pension (which doesn't inflate). If you have a fixed pension, enter a slightly lower amount to simulate the real-value erosion, or add the pension income conservatively.
A plan where income events cover most expenses effectively makes the portfolio much more resilient. This can be accurate if your income events are reliable and large. The sensitivity to check is whether the events are guaranteed (SS, pension) or uncertain (consulting, rental income that might dry up). Conservative modeling would reduce uncertain events by 25-50% to account for that risk.