Retirement Calculator — Nest Egg & 4% Rule Projection
Project your retirement nest egg from savings and monthly contributions, then estimate annual income with the 4% rule in nominal and today’s dollars.
About Retirement Calculator
A retirement calculator is a tool that projects how large a retirement nest egg your current savings could grow into, then estimates the yearly income that pot might support. It takes your current savings, your monthly contributions, an assumed annual investment return, and the years until you retire, and compounds them forward to a projected balance. It then applies the 4% "safe withdrawal" guideline to estimate a sustainable annual income, and discounts the result for inflation so you see both a nominal (future-dollar) figure and a real (today’s-dollar) figure. Long-horizon projections swing widely with the return and inflation you assume, so treat every number as an illustration, not a promise. This is not financial advice.
Use cases
- Turn a vague goal into a target number. "Save for retirement" is hard to act on; a projected balance and the income it could produce make it concrete. Seeing that a given monthly contribution grows to a specific nest egg — and roughly what yearly income the 4% rule draws from it — helps you judge whether your current pace is on track or needs adjusting well before retirement arrives.
- Compare contribution levels side by side. Because the projection updates from your inputs, you can try different monthly contributions and watch how much difference an extra amount makes over decades. Compounding rewards consistency and time, so a modest increase sustained for many years often moves the final balance far more than people expect, which is a powerful reason to start early.
- See today’s-dollar value, not just a big number. A seven-figure future balance can be misleading because inflation erodes what money buys. The real, inflation-adjusted figure translates the projection into today’s dollars, giving a more honest sense of the lifestyle it could fund. Comparing the nominal and real numbers side by side shows just how much inflation quietly matters over a long horizon.
- Stress-test your return and inflation assumptions. Because long projections are so sensitive to the rates you choose, entering a more cautious return and a higher inflation rate reveals how fragile an optimistic plan can be. Running both an optimistic and a conservative scenario brackets a realistic range of outcomes, which is far more useful for planning than trusting a single confident-looking number.
- Sanity-check the 4% withdrawal idea. The 4% rule is a rough guideline that a portfolio might sustain annual withdrawals of about 4% of its starting value. Seeing that figure attached to your projected balance helps you gauge whether the income would cover your expected needs, while reminding you that the rule is a starting assumption, not a guarantee that the money will last.
How it works
- Enter your current savings. Start with the total you have already set aside for retirement across your accounts.
- Add your monthly contribution. Enter how much you plan to add each month; this is compounded along with your starting balance.
- Set your assumed annual return. Choose a realistic growth rate for your investments — this single input has an outsized effect on the result.
- Enter years to retirement and inflation. Give the number of years until you retire and an expected inflation rate so the tool can show today’s-dollar values.
- Read the projected balance and income. The calculator shows the nominal and inflation-adjusted nest egg and applies the 4% rule to estimate a sustainable annual income.
Examples
Input: $50,000 saved, $500/mo, 7% return, 30 years, 3% inflation
Output: ≈ $990,000 nominal (~$408,000 in today’s dollars)
The 4% rule implies roughly $40,000/year nominal — a vivid example of how inflation shrinks the real figure.
Input: $0 saved, $300/mo, 6% return, 40 years, 2.5% inflation
Output: ≈ $598,000 nominal (~$223,000 in today’s dollars)
Starting from zero, four decades of steady $300 contributions still compound substantially — time is the biggest lever.
Input: Same inputs but a 5% return instead of 7%
Output: The projected balance drops sharply
A two-point change in assumed return can swing a long projection by hundreds of thousands — a reason to test conservative rates.
Frequently asked questions
What is the 4% rule?
It is a rule of thumb from retirement research suggesting that withdrawing about 4% of your portfolio’s starting value each year, then adjusting for inflation, has historically had a reasonable chance of lasting roughly 30 years. It is a guideline based on past markets, not a guarantee for the future.
Why does the tool show nominal and real numbers?
The nominal figure is the raw future balance; the real figure discounts it for inflation to show what it would be worth in today’s dollars. Over decades, inflation makes a big number buy much less, so the real value is usually the more meaningful one for planning.
How accurate is a 30- or 40-year projection?
It is an illustration, not a forecast. Real returns vary year to year, inflation shifts, and contributions change. The result depends heavily on assumptions you cannot know in advance, so use it to compare scenarios rather than to predict an exact balance.
What return rate should I use?
There is no correct number. Long-run stock returns have often been cited around 7% before inflation, but the future may differ and your mix of investments matters. Because the result is so sensitive to this input, it is wise to run a conservative rate as well.
Does it account for taxes and fees?
No. This is a simplified projection that ignores taxes, investment fees, employer matches, and Social Security or pensions. A real plan should factor those in, which is where a financial professional can help.
Is my data saved or shared?
No. All calculations happen in your browser. Nothing you enter is uploaded or stored by the tool.
Is this financial advice?
No. It is an educational estimate. For decisions about how much to save, how to invest, or when to retire, consult a qualified financial advisor who can consider your full circumstances.
Pro tips
- Run at least two scenarios — one optimistic, one conservative — to bracket a realistic range.
- Focus on the today’s-dollar (real) figure; the big nominal number overstates your future buying power.
- Small increases to your monthly contribution compound heavily over decades — try nudging it up.
- Remember the projection ignores taxes, fees, and other income such as Social Security or a pension.
- Revisit the calculation yearly and update it as your savings, contributions, and goals change.
Reviewed by Ahsan Mahmood · Last updated 2026-07-08 · Part of ZTools.
For the full,
formatted version of this page, please enable JavaScript and reload
https://ztools.zaions.com/retirement-calculator.