Retirement Planner Calculator
Two Numbers Have to Meet: What You'll Have and What You'll Need
Most retirement questions eventually reduce to a single comparison — the balance your current savings plan will actually produce, against the balance required to support your desired income for as long as you need it. This calculator runs both sides of that comparison at once: it projects your savings forward using your contribution and return assumptions, and it works backward from your desired income (inflated to your retirement date) to a required nest egg using your withdrawal rate.
The Formula
Future Desired Income = Desired Income × (1 + Inflation Rate)years
Required Nest Egg = Future Desired Income ÷ Withdrawal Rate
The gap between the two — projected savings minus required nest egg — is reported as a surplus or shortfall, telling you directly whether the current plan is on track.
Where This Calculation Matters
- Mid-career check-ins — running this every few years catches a shortfall early enough to fix it with a modest contribution increase rather than a drastic one.
- Setting a realistic retirement age — if the numbers show a shortfall at 65, testing 67 or 70 shows how much extra time closes the gap.
- Adjusting for inflation explicitly — inflating today's desired income to future dollars avoids the common mistake of comparing a future balance to a present-day spending target.
- Evaluating a withdrawal rate assumption — a lower assumed withdrawal rate raises the required nest egg, which is a useful stress test for retirement plans.
A Worked Example
| Quantity | Value |
|---|---|
| Years to retirement | 35 |
| Projected savings at 65 | $1,130,650.34 |
| Desired income inflated to age 65 | $142,392.31 / year |
| Required nest egg (at 4% withdrawal) | $3,559,807.78 |
| Shortfall | −$2,429,157.44 |
This example illustrates how a high desired income relative to contributions produces a large shortfall — raising the monthly contribution, extending the timeline, or accepting a lower retirement income would each narrow the gap.
How to Use This Calculator
- Enter your current age and planned retirement age.
- Enter your current retirement savings and planned monthly contribution.
- Enter the annual return rate you expect.
- Enter your desired annual retirement income in today's dollars.
- Enter your intended withdrawal rate (default 4%) and expected inflation rate (default 0%).
- Select Calculate to see your projected savings, required nest egg, and whether you're on track or facing a shortfall.
Related Calculations
Break the projection down further with the Retirement Savings Calculator, or see how a shortfall changes once Social Security is added using the Retirement Income Calculator.