The two phases of the plan
Retirement planning has a build-up and a wind-down. During accumulation, your current savings and monthly contributions compound at your working-years return, growing the nest egg until the day you retire. During drawdown, you stop contributing and instead pull a fixed amount out each month while the remaining balance still earns a (usually lower) return.
The calculator simulates both phases month by month and reports the nest egg you reach at retirement, whether the money survives to your end age, and any surplus or shortfall left over.
Reading the charts
The line chart shows the balance rising through your working years and then declining once withdrawals begin — a classic hump shape. If the line hits zero before your end age, the plan runs short.
The donut breaks the nest egg at retirement into the dollars you actually contributed versus the investment growth on top. Early in a career the contributions dominate; given enough time, growth can become the larger slice.
If the money runs short
When funds do not last, several adjustments can close the gap:
- Contribute more each month during your working years.
- Delay retirement so savings grow longer and the drawdown is shorter.
- Lower the monthly withdrawal in retirement.
- Aim for a higher (but realistic) return, keeping in mind the added risk.
Important assumptions
Returns and withdrawals are nominal — inflation is not modeled, so future dollars are not adjusted for lost purchasing power. Taxes, Social Security, pensions, and variable market returns are also excluded. To approximate inflation, use a lower assumed return or a higher withdrawal.
Formula
Accumulate monthly to retirement, then draw down monthly to the end ageFrequently asked questions
- Does this account for inflation or taxes?
- No. Returns and withdrawals are in nominal terms. To approximate inflation, lower your assumed returns or raise your planned withdrawal.

