What this calculator does
A retirement projection has two halves that are usually calculated separately: building the balance, and spending it. This calculator does both. It grows what you have plus what you contribute up to your retirement age, then draws the balance down at your chosen withdrawal rate and reports how long it lasts.
The two halves use different return rates, which reflects normal practice: portfolios are typically held more conservatively once income is being drawn. If withdrawals happen to be smaller than the return the balance earns, the calculator says so rather than reporting a finite number of years.
The formula
The accumulation phase uses the compound interest formula with regular contributions. The drawdown phase inverts it, solving for the number of periods a balance supports at a given withdrawal. If the withdrawal is below the return earned, the balance never depletes.
| Term | Meaning |
|---|---|
| B | The balance at retirement, at the end of the accumulation phase. |
| i | Monthly return before retirement. |
| j | Monthly return during retirement. |
| W | The monthly withdrawal in retirement. |
The inputs explained
| Field | What to enter |
|---|---|
| Current age | Your age now. |
| Retirement age | The age you plan to stop working. |
| Current balance ($) | The total currently in retirement accounts. |
| Contribution per month ($) | Total monthly contributions, including any employer contribution. |
| Return before retirement (%) | Expected annual return while still working. |
| Return in retirement (%) | Expected annual return once retired: usually lower, as portfolios tend to become more conservative. |
| Withdrawal per month in retirement ($) | What you expect to withdraw each month once retired, in today’s dollars. |
When to use it
Checking whether you are on track
Enter your real numbers. If the balance runs out before a plausible life expectancy, the projection is telling you something useful now, while there is still time to act on it.
Testing the value of extra contributions
Raise the monthly contribution and watch both the retirement balance and the number of years it lasts. Contributions made in your thirties have decades to compound; the same amount in your late fifties does not.
Choosing a retirement age
Retiring later helps three times over: more contributions, more growth, and fewer years to fund. Moving the retirement age by two or three years usually shifts the outcome more than any other single change.
Setting a sustainable withdrawal
Adjust the withdrawal until the balance lasts as long as you need. That figure, not a rule of thumb, is what your own numbers support.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the retirement age changes the outcome
A 35-year-old with $80,000 saved and $900 a month going in, at a 7% pre-retirement return, withdrawing $8,000 a month afterwards.
| Retirement age | Balance at retirement | Investment growth | Savings last |
|---|---|---|---|
| Age 55 | $791,933.10 | $495,933.10 | 10.0 years (to age 65.0) |
| Age 60 | $1,187,097.98 | $837,097.98 | 17.1 years (to age 77.1) |
| Age 62 | $1,388,045.33 | $1,016,445.33 | 21.6 years (to age 83.6) |
| Age 65 | $1,747,293.69 | $1,343,293.69 | 32.6 years (to age 97.6) |
| Age 67 | $2,032,161.73 | $1,606,561.73 | 47.0 years (to age 114.0) |
| Age 70 | $2,541,441.29 | $2,083,441.29 | indefinitely: withdrawals are below the return |
The effect of monthly contributions
Thirty years of accumulation at 7%, then $8,000 a month drawn at 4%.
| Contribution per month | Balance at retirement | Total contributed | Savings last |
|---|---|---|---|
| $250 | $954,312.55 | $170,000.00 | 12.7 years (to age 77.7) |
| $500 | $1,259,305.30 | $260,000.00 | 18.6 years (to age 83.6) |
| $900 | $1,747,293.69 | $404,000.00 | 32.6 years (to age 97.6) |
| $1,500 | $2,479,276.29 | $620,000.00 | indefinitely: withdrawals are below the return |
| $2,500 | $3,699,247.29 | $980,000.00 | indefinitely: withdrawals are below the return |
How the withdrawal rate changes longevity
The same accumulation in every row, with only the monthly withdrawal changing.
| Monthly withdrawal | Balance at retirement | Savings last |
|---|---|---|
| $3,000 | $1,747,293.69 | indefinitely: withdrawals are below the return |
| $4,000 | $1,747,293.69 | indefinitely: withdrawals are below the return |
| $5,000 | $1,747,293.69 | indefinitely: withdrawals are below the return |
| $6,000 | $1,747,293.69 | 88.4 years (to age 153.4) |
| $8,000 | $1,747,293.69 | 32.6 years (to age 97.6) |
Questions
Does this include the age pension or social security?
No. Government benefits vary by country, are means-tested in many places, and change over time. Treat this as covering your own savings, and add any expected benefit to the income side separately.
Is the result adjusted for inflation?
No, it is in nominal dollars. For a rough real-terms view, use real returns, subtract expected inflation from both return rates, and enter withdrawals in today’s dollars.
Why does it sometimes say savings last indefinitely?
Because the return on the balance exceeds the withdrawals, so the balance grows rather than depletes. That is mathematically true at a constant return, though real returns vary and a bad early sequence can undo it.
What return rates are reasonable?
There is no single answer. Long-run diversified portfolio returns have historically sat in the mid-to-high single digits before inflation, with wide variation by decade. Running the projection at several rates gives a more honest picture than one number.
How long should I plan for?
Longer than average life expectancy, since planning to the average means a coin-flip chance of outliving the money. Many advisers plan to age 90 or beyond.
To see what a fixed balance pays out as income, use the annuity payout calculator. For the accumulation maths alone, see compound interest.