Transparent method
The formula
Worked example
Example inputs
How to interpret the result
The years and contributions required to reach a million-dollar target are highly sensitive to the assumed rate of return, and that projection also runs against taxes and fees that steadily eat into real, spendable growth over a long enough horizon. A headline projection that ignores both tends to arrive at an optimistic timeline.
Before you rely on it
What to check
Run the projection at more than one return assumption and account for the drag of taxes and fees, rather than trusting a single optimistic projection with neither included.
The common error
Where people go wrong with millionaire calculator
Projecting years to a million-dollar target using an optimistic return assumption with no allowance for taxes or fees. Both reduce real growth over a long horizon, and ignoring them produces a timeline shorter than what's actually realistic.
Sensitivity evidence
How expected annual return changes the estimated time to target
| Expected annual return | Estimated time to target | Total contributions through target | Estimated investment growth |
|---|---|---|---|
| 5.0% | 21.8 years | $491,500 | $510,170 |
| 6.0% | 19.8 years | $455,500 | $548,918 |
| 7.0%worked example | 18.1 years | $425,500 | $579,153 |
| 8.0% | 16.7 years | $400,000 | $602,499 |
| 9.0% | 15.5 years | $379,000 | $625,208 |
Every input, tested
Which input moves the estimated time to target most
| Input | Tested from | To | Estimated time to target at each end | Swing |
|---|---|---|---|---|
| Expected annual return | 6.0% | 8.0% | 19.8 years to 16.7 years | 3.1 years (17%) |
| Target balance | $900,000 | $1,100,000 | 16.9 years to 19.2 years | 2.3 years (12%) |
| Monthly investment | $1,350 | $1,650 | 18.8 years to 17.3 years | 1.5 years (8.3%) |
| Current invested balance | $90,000 | $110,000 | 18.5 years to 17.7 years | 0.8 years (4.6%) |
Two variables at once
Estimated time to target by expected annual return and current invested balance
| Expected annual return \ Current invested balance | $80,000 | $100,000 | $120,000 |
|---|---|---|---|
| 5.0% | 22.7 years | 21.8 years | 20.9 years |
| 6.0% | 20.6 years | 19.8 years | 18.9 years |
| 7.0% | 18.9 years | 18.1 years | 17.3 years |
| 8.0% | 17.5 years | 16.7 years | 15.9 years |
| 9.0% | 16.3 years | 15.5 years | 14.8 years |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Current invested balance | $100,000 |
| Monthly investment | $1,500 |
| Expected annual return | 7.0% |
| Target balance | $1,000,000 |
| Estimated time to target | 18.1 years |
| Total contributions through target | $425,500 |
| Estimated investment growth | $579,153 |
Where the inputs come from
Current invested balance is what you have in investment accounts today, monthly investment is what you add, expected return is your assumption after fees, and target balance is the goal, here $1 million. The tool iterates growth and deposits until the target is reached, so the result is the time. Use a conservative return and increase your contribution in the model when you expect raises. Include only money you intend to leave invested.
When the result stops applying
A million dollars in the future buys less than a million today, so the goal should be adjusted for inflation. The model assumes a steady return and consistent deposits, while real markets swing and incomes change. It ignores taxes on gains and fees. Reaching the number is not the same as being able to retire, which depends on spending.
What to compare it with
Test other targets with the time to save and savings goal calculators, and check retirement readiness with the retirement goal page. The compound interest and dollar-cost averaging pages show the growth math. The rule of 72 gives a fast estimate of doubling time.
People also ask
Frequently asked questions
How long does it take to become a millionaire?
It depends on the balance, the monthly saving and the return. With $100,000 saved, $1,500 a month and a 7% return, about 18 years.
What matters more, contributions or returns?
Early on, contributions dominate. Later, growth becomes the larger share, which is why starting early and staying invested matter.
Is a million dollars enough to retire?
It depends on spending and other income. A 4% withdrawal from $1 million gives about $40,000 a year, before adding Social Security.