Retirement planning comes down to one question: will the money you set aside, plus the growth it earns, be enough to support the lifestyle you want after you stop working? This calculator projects your nest egg by combining your current savings, ongoing contributions, expected investment return, and the number of years until you retire.
How the projection works
Your balance grows in two ways: the contributions you add each year, and the compound returns those contributions earn over time. The calculator applies your expected annual return to a growing balance, so the earnings themselves start earning — which is why starting early matters far more than the amount you contribute.
The power of starting early
Someone who invests $500 a month from age 25 to 65 at a 7% return retires with roughly $1.2 million. Someone who waits until 35 and invests the same $500 a month ends up with about $570,000 — less than half — despite contributing only ten fewer years. The extra decade of compounding does the heavy lifting.
How much you will need
A common benchmark is the 4% rule: you can withdraw about 4% of your balance in the first year of retirement and adjust for inflation thereafter. That means a $1 million portfolio supports roughly $40,000 of annual spending. Work backward from your desired retirement income to see the target balance you should aim for.
Ways to strengthen your plan
- Capture every dollar of employer 401(k) match — it is an instant 50-100% return.
- Increase your contribution rate by 1% each year, ideally timed with raises so you never feel the cut.
- Keep fees low; a 1% annual fee can cost you hundreds of thousands over a career.
- Revisit your expected return assumption conservatively — planning for 6-7% rather than 10% leaves margin for down years.
The cost of waiting: same savings, different start ages
The table compares three savers who each put away $500 a month, earn an average 7% annual return compounded monthly, and stop at age 67. The only difference is when they start.
| Start age | Years saving | Total contributed | Balance at 67 | Income at 4%/yr |
|---|---|---|---|---|
| 25 | 42 | $252,000 | about $1,522,000 | about $60,900 |
| 35 | 32 | $192,000 | about $714,000 | about $28,600 |
| 45 | 22 | $132,000 | about $312,000 | about $12,500 |
The 25-year-old contributes only $60,000 more than the 35-year-old but ends up with more than twice as much, because those extra ten years give compounding time to work. For a late starter the lesson is not to give up but to save more: the 45-year-old would need to set aside roughly $1,150 a month to reach the same balance as the 35-year-old saving $500.
Turning a balance into income
A widely cited starting point is the 4% guideline, based on historical research suggesting that withdrawing about 4% of a diversified portfolio in the first year, then adjusting for inflation, has usually lasted around 30 years. It is a rule of thumb, not a promise. Retiring early, holding a very conservative portfolio, or hitting a market downturn right after retiring can all argue for a lower withdrawal rate.
Most retirees also receive Social Security. In 2026 the benefit formula replaces 90% of average indexed monthly earnings up to $1,286, 32% up to $7,749, and 15% above that, so it replaces a larger share of income for lower earners. Subtract your estimated benefit from your spending target to see how much your savings actually need to cover.
Assumptions worth stress-testing
- Return rate: try 5% and 8% as well as 7% to see a realistic range.
- Inflation: $1 million in 30 years will buy far less than today. At 3% inflation, prices roughly double every 24 years.
- Taxes: withdrawals from traditional 401(k)s and IRAs are taxed as ordinary income; qualified Roth withdrawals are not.
- Healthcare: Medicare begins at 65, so anyone retiring earlier needs a plan for health insurance premiums.
- Longevity: plan for a retirement that lasts into your 90s, especially if you are married.
Finally, treat this projection as a checkpoint rather than a verdict. Revisit it once a year, when you change jobs, or after a big life event. If you are behind, the most effective levers are, in order: saving a higher percentage of income, capturing every dollar of employer match, working a year or two longer (which adds contributions, adds growth, and shortens the withdrawal period), and delaying Social Security, which permanently increases the monthly benefit for each year you wait past full retirement age, up to age 70.