Project an investment with a starting amount, regular contributions and a yearly return. Raise your contributions each year, or work out how much you need to invest to hit a target.
How it's calculated
Investment returns are quoted per year, so Calcist converts the yearly return to the matching monthly rate rather than dividing by 12:
i = (1 + yearly return)1/12 − 1 (7% a year → 0.5654% a month)
Each period, the balance grows by i and your contribution is added (before the growth if you choose "Start of period"). After each 12 months, the contribution rises by your yearly increase. With no increase, this is the standard future value formula:
FV = P(1 + i)ⁿ + C × ((1 + i)ⁿ − 1) ÷ i
This is why the compound interest and future value calculators give a higher number for what looks like the same input. They treat 7% as a rate compounded monthly (7% ÷ 12 = 0.5833% a month), which is really 7.23% a year, and give $300,850.72 for the example below instead of $292,465.03. Use those pages for a quoted interest rate, and this one for a yearly return.
To find the contribution needed, Calcist uses the fact that the end balance rises in a straight line with the contribution: C = (target − what the starting amount grows to) ÷ (what $1 a period grows to).
Worked example
$10,000 to start plus $500 a month at 7% a year for 20 years grows to $292,465.03: $130,000 of your money and $162,465.03 of growth. Raise the $500 by 3% each year (to $515 in year 2, $530.45 in year 3 and so on) and it grows to $358,042.47. To reach $1,000,000 in the same 20 years you'd need about $1,894.06 a month.
Limitations
- Returns aren't steady. A fixed 7% is an assumption. Real markets swing from year to year, and the order of good and bad years changes the result when you add or withdraw money.
- Fees and taxes. Enter the return after fund fees. Taxes on dividends and gains in a taxable account aren't included.
- Inflation. The result is in future dollars. Subtract inflation from the return (7% − 3% ≈ 4%) for a rough figure in today's dollars, or use the savings calculator, which shows both.
This is a planning estimate, not financial, tax or investment advice.
Sources
How we checked this
Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:
- $10,000 + $500 a month at 7% for 20 years = $292,465.03 ✓
- Same, raising the contribution 3% a year = $358,042.47 ✓
- $6,000 at the start of each year at 7% for 30 years = $606,438.25 ✓
- $1,000,000 in 20 years from $10,000 at 7% needs $1,894.06 a month ✓
- Same inputs, 7% ÷ 12 convention noted: $300,850.72 ✓
- −99% return: says you lost money ✓
- 0% return: $1,000 + $100 a month for 10 years = $13,000 ✓
Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.
Questions people ask
How much will I have if I invest $500 a month?
At a 7% yearly return, $500 a month for 20 years grows to about $253,768 with no starting amount, and $292,465 with $10,000 to start. Change the return and years above to see your numbers.
How much do I need to invest each month to reach $1 million?
Choose "Contribution needed" and enter $1,000,000. Starting from $10,000 with a 7% return, it's about $1,894 a month over 20 years or about $790 a month over 30 years.
What return should I use?
Use what you realistically expect after fees. Stock funds have had higher long-run returns than bonds or cash, but with large swings. Try a low, middle and high number to see the range.
Does contributing at the start of the month make a difference?
A little. Each contribution gets one more month of growth, so the balance ends slightly higher, about one month's return on the total.
Why raise contributions each year?
Most people's pay rises over time. Increasing what you invest by even 2–3% a year adds a lot over decades, as the example shows.