Retirement savings calculator
Project contributions toward a future retirement balance.
- Formula and assumptions shown
- Table and CSV export
- Runs in your browser
How it works
The model compounds current savings and recurring contributions until the entered retirement age. It treats the entered annual return as a nominal rate, divides it by 12, and compounds monthly; contributions are added at month end. The corresponding effective annual growth rate is (1 + annual return ÷ 12)^12 − 1, which can differ from the entered rate. The model also translates the future balance into today's purchasing-power terms using your inflation assumption.
Monthly rate = nominal annual return ÷ 12; each month, the balance compounds at that rate and the contribution is added at month end. Future balance = compounded current savings + compounded recurring contributions; real value = future balance ÷ (1 + inflation)^years.
This is a scenario calculator, not a retirement recommendation. It does not forecast markets, benefits, taxes, healthcare, or a sustainable withdrawal rate.
Assumptions
- The entered annual return is interpreted as a nominal rate, divided by 12, and compounded monthly; its effective annual growth rate is (1 + annual return ÷ 12)^12 − 1.
- Inflation remains constant and is compounded annually for the purchasing-power conversion.
- Monthly contributions stay level and are added at month end after that month's interest is calculated.
- The projection ends at the entered retirement age without withdrawals, with a maximum horizon of 50 years.
- Taxes, employer matches, fees, contribution limits, benefits, and return volatility are not modeled.
Worked example
$25,000 saved at age 35
With $500 added monthly, a 6% annual return assumption, 2% inflation, and retirement at 45, the model projects about $127,424.59 nominally and $104,532.55 in today's dollars.
Step by step
- Monthly rate and months. 6% ÷ 12 = 0.5% a month. Retiring at 45 from age 35 gives (45 − 35) × 12 = 120 month-end contributions.
- Growth of current savings. 1.005^120 = 1.819397, so $25,000 grows to $25,000 × 1.819397 = $45,484.92.
- Growth of contributions. $500 × (1.819397 − 1) ÷ 0.005 = $500 × 163.879347 = $81,939.67, built from $60,000 of deposits.
- Projected balance. $45,484.92 + $81,939.67 = $127,424.59 at age 45.
- Today’s dollars. With 2% inflation, prices rise by 1.02^10 = 1.218994 over 10 years, so $127,424.59 ÷ 1.218994 = $104,532.55 in today’s purchasing power.
How to read your result
Projected retirement balance is the nominal amount in the account at the retirement age. Inflation-adjusted balance restates it in today’s dollars, which is the better figure for comparing with current spending. Contributions is the total of the monthly deposits, not counting current savings, and Years to retirement is the length of the projection.
The breakdown splits the final balance into current savings, contributions, and investment growth. In the example, $25,000 of starting savings and $60,000 of deposits become $127,424.59, so $42,424.59 is growth. The yearly table and chart show the nominal balance and its value in today’s dollars at each age; the gap between the two lines widens with time.
The projection is before taxes and fees. Balances in pre-tax accounts such as a traditional 401(k) are taxed when withdrawn, and fund fees lower the return actually earned. Employer matches are not added automatically, so include them in the monthly contribution. Annual contribution limits are not enforced, and the return is constant every month, so the path is smoother than any real market.
What changes the result most
- Return assumption
- At 5% instead of 6%, the example reaches $118,816.38, which is $8,608.21 less; at 7% it reaches $136,783.94. The effect grows with the length of the projection.
- Years until retirement
- Retiring at 55 instead of 45 raises the projection to $313,775.56 ($211,161.96 in today’s dollars) while deposits only double from $60,000 to $120,000, because the earlier balance compounds for 10 more years.
- Monthly contribution
- Contributing $750 instead of $500 raises the balance at 45 to $168,394.43, which is $40,969.84 more from $30,000 of extra deposits.
- Inflation
- At 3% inflation instead of 2%, the nominal balance is unchanged but its value in today’s dollars falls to $94,815.86.
Questions
Is the return guaranteed?
No. The return is an assumption used to illustrate a scenario. Actual investment results can be higher, lower, or negative.
Why show today's dollars?
A future dollar may buy less than a current dollar. The inflation-adjusted view helps you compare the projection with today's spending needs.
Is the entered annual return an effective annual rate?
No. It is treated as a nominal annual rate, divided by 12, and compounded monthly. For example, a 6% nominal input corresponds to an effective annual growth rate of (1 + 0.06 ÷ 12)^12 − 1, or about 6.17%, before rounding.
Does this tell me when I can retire?
No. It projects a balance at one chosen age. A complete retirement decision also needs spending, taxes, healthcare, benefits, and withdrawal assumptions.
How much money do I need to retire?
There is no single figure. It depends on expected spending, other income such as Social Security or a pension, taxes, the age you stop working, and how long the money needs to last. One way to frame it is to estimate annual spending that other income will not cover and divide it by a withdrawal-rate assumption, which is what the FIRE calculator does; the retirement withdrawal calculator then shows how a balance behaves under a chosen spending plan. The Social Security Administration provides personal benefit estimates through my Social Security.
How much should I save for retirement?
No percentage fits everyone. The amount depends on the target balance, the years left, and the return assumed, and on whether an employer matches contributions. This calculator shows the effect of a change directly: in the example, adding $250 a month adds $40,969.84 by age 45. The IRS sets annual contribution limits for 401(k) plans and IRAs, and those limits change most years.
More in Retirement
- Retirement savings
- Retirement withdrawal
- FIRE
Sources
These references explain the concepts behind the calculation. They do not endorse this site. Estimates leave out any cost or condition you did not enter.