Investing $100 a month at the stock market's long-term average of 10% a year, you reach $1 million in about 46 years and 1 month. Here's how the timeline changes with different returns, starting ages and goals.
Time to $1 Million Investing $100 a Month
| Annual return | Time to $1 million | You contribute | Compound growth |
|---|---|---|---|
| 6% a year | 67 years and 1 month | $80,500 | $919,500 |
| 8% a year | 54 years and 4 months | $65,200 | $934,800 |
| 10% a year | 46 years and 1 month | $55,300 | $944,700 |
Reference rates (October 2026): high-yield savings 4.20% APY, 1-year CD 4.40%, 3-month T-bills 4.20%, dividend ETF yield ~3.7%, stock market long-term average 10% a year (7% after inflation). Figures are before taxes: interest is taxed as ordinary income, qualified dividends at lower rates. Sources: CNBC Select and NerdWallet (savings and CD rates, Oct 2026), U.S. Treasury (3-month bill), BLS Consumer Expenditure Survey (household spending). Not financial advice.
At What Age Will You Be a Millionaire?
| Starting age | Millionaire at (10% nominal) | In today's dollars (7% real) |
|---|---|---|
| 25 | 72 | 85 |
| 30 | 77 | 90 |
| 35 | 82 | 95 |
| 40 | 87 | 100 |
| 45 | 92 | 105 |
The "today's dollars" column accounts for ~3% inflation: $1 million in the future buys less than $1 million today. See S&P 500 historical returns for why 10% is the usual long-term assumption.
Other Goals with $100 a Month
| Goal | Time at 10% a year |
|---|---|
| $250,000 | 31 years and 11 months |
| $500,000 | 39 years |
| $2 million | 53 years and 4 months |
How to Get There Faster
- Use a 401(k) match — it's an instant 50–100% return on your contribution.
- Keep costs low — broad index funds charge 0.03–0.10% a year.
- Increase $100 over time — raising it 5% a year cuts years off the timeline.
- Stay invested in down markets — buying during drops is what makes the average work.
Frequently Asked Questions
How long does it take to save $1 million investing $100 a month?
At the stock market's long-term average of 10% a year, investing $100 a month gets you to $1 million in about 46 years and 1 month. At a more conservative 6%, it takes about 67 years and 1 month.
How much of the $1 million is my own money?
At 10% a year you contribute about $55,300; the remaining $944,700 comes from compound growth.
What is $1 million worth after inflation?
Measured in today's dollars (7% real return), reaching $1 million of purchasing power takes about 59 years and 11 months investing $100 a month.
How much monthly income does $1 million produce?
With the 4% rule, $1 million supports about $3,333 a month. In a high-yield savings account at 4.20%, it earns about $3,500 a month in interest.