At 4%, the $100,000 target arrives after 7 years and 3 months. The investor contributes $87,000, while modeled growth adds about $13,735.
How long would it take to reach $100,000 by investing $1,000 at the end of every month? With no investment return, the answer is 100 months, or 8 years and 4 months. At a steady 4% annual return compounded monthly, the target arrives in month 87.
By then, the investor has contributed $87,000. Modeled growth adds about $13,735, taking the balance to roughly $100,735 after 7 years and 3 months.
The 4% path reaches the target in month 87
The first year is driven almost entirely by contributions. Twelve deposits add up to $12,000, while the modeled balance is about $12,222. Investment growth accounts for only about $222.
The balance begins to separate more clearly from the money contributed as the earlier deposits and their gains remain invested.
| Time elapsed | Money contributed | Modeled balance | Investment gain |
|---|---|---|---|
| 1 year | $12,000 | About $12,222 | About $222 |
| 3 years | $36,000 | About $38,182 | About $2,182 |
| 5 years | $60,000 | About $66,299 | About $6,299 |
| 6 years | $72,000 | About $81,223 | About $9,223 |
| 7 years | $84,000 | About $96,754 | About $12,754 |
| 7 years, 3 months | $87,000 | About $100,735 | About $13,735 |
At the seven-year mark, the account is still about $3,246 short of the target. Three more $1,000 deposits, plus another three months of modeled growth on the existing balance, carry it past $100,000.
The return assumption changes both time and contributions
Every scenario below starts at $0, adds $1,000 at each month-end, and stops in the first month the balance reaches at least $100,000.
| Annual-return assumption | Time to $100,000 | Total contributed | Modeled gain | Balance when target is reached |
|---|---|---|---|---|
| 0% | 8 years, 4 months | $100,000 | $0 | $100,000 |
| 4% | 7 years, 3 months | $87,000 | About $13,735 | About $100,735 |
| 6% | 6 years, 10 months | $82,000 | About $19,056 | About $101,056 |
| 8% | 6 years, 5 months | $77,000 | About $23,201 | About $100,201 |
The 4% scenario reaches the goal 13 months earlier than the 0% case. Moving from 4% to 6% shortens the timeline by another five months. Moving from 4% to 8% shortens it by ten months.
A higher return also reduces the number of deposits
At 4%, the investor makes 87 deposits and contributes $87,000. At 8%, the target is crossed after 77 deposits, so total contributions are $77,000.
That $10,000 difference is replaced by more modeled investment growth. The 8% scenario has about $23,201 of growth when it crosses the target, compared with about $13,735 at 4%.
This does not mean an investor can choose an 8% return or expect it to arrive smoothly. The comparison isolates how the target date changes when only the assumed return changes.
The calculation uses end-of-month deposits
The annual return is divided by 12 and applied to the balance already in the account. The new $1,000 contribution is then added at the end of the month.
The first deposit has more than seven years to earn a return in the 4% scenario. The last deposit enters in month 87 and has no additional month to grow before the calculation stops. This is why the result differs from investing $87,000 as a lump sum on the first day.
Depositing at the beginning of each month, increasing the monthly amount, adding a bonus, or starting with an existing balance would all change the target date.
Actual investing will not follow a fixed monthly return
Stocks and funds do not produce the same return every month. Even if a portfolio eventually averages 4% a year, the order of gains and losses can move the date when the balance first crosses $100,000.
Taxes, fund expenses, trading costs, and missed deposits can delay the goal. Inflation also changes what $100,000 can buy by the time the target is reached.
The 4%, 6%, and 8% figures are comparison assumptions, not promised returns or forecasts for any investment.
Change the target in the calculator
ReturnLab's recurring-investment calculator can use the same starting balance of $0, monthly contribution of $1,000, and target of $100,000. The duration mode compares the 4%, 6%, and 8% target dates side by side.
Changing the contribution to $500 or $1,500, or adding money already saved, recalculates how long the same target would take.