How to use
- Enter the regular contribution and how often you make it, plus any starting amount.
- Enter the expected annual return and the number of years.
- Read the final balance, total contributions and growth, and check the year-by-year table.
Options explained
- Expected annual return
- An assumed average return. Stock funds have historically averaged roughly 6–10% a year over long periods, with large swings between years; no rate is guaranteed.
- Contribution timing
- Contributions are made at the start of each period by default, which earns one extra period of growth. Switch it in the timing option.
- Compounding
- Monthly compounding by default, matching monthly contributions.
Examples (monthly compounding, contributions at the start of each month)
| Monthly | Return | Years | Paid in | Final balance | Growth |
|---|---|---|---|---|---|
| 1,000 | 8% | 10 | 120,000 | 184,165.68 | 64,165.68 |
| 1,000 | 8% | 20 | 240,000 | 592,947.22 | 352,947.22 |
| 500 | 6% | 30 | 180,000 | 504,768.81 | 324,768.81 |
| 2,000 | 5% | 5 | 120,000 | 136,578.88 | 16,578.88 |
What 500 a month can grow to
Investing 500 at the start of every month, with returns compounded monthly:
| Years | Paid in | 4% a year | 6% a year | 8% a year | 10% a year |
|---|---|---|---|---|---|
| 5 | 30,000 | 33,260 | 35,059 | 36,983 | 39,041 |
| 10 | 60,000 | 73,870 | 82,349 | 92,083 | 103,276 |
| 20 | 120,000 | 183,999 | 232,176 | 296,474 | 382,848 |
| 30 | 180,000 | 348,181 | 504,769 | 750,148 | 1,139,663 |
Over short periods most of the balance is your own money; over decades, growth on growth takes over — after 30 years at 8%, three quarters of the balance is investment growth.
Starting early versus investing more later
Two savers each put in 144,000 at 7% a year:
Early starter: 300 a month for 40 years grows to about 792,000.
Late starter: 600 a month for 20 years grows to about 314,000.
The same total paid in ends up more than twice as large, simply because it has twice as long to compound.
Returns are not guaranteed — stock markets rise and fall, and long-run averages hide bad years. Use a lower rate to see a cautious scenario, and remember that fees and inflation reduce real returns.
Frequently asked questions
Will my investments really grow this much?
The calculator assumes a steady return, while real markets rise and fall. Use it to compare amounts and time frames rather than as a forecast.
How long should I invest for?
Regular investing works best over many years — try changing 10 years to 20 to see how compounding accelerates the result.
Are fees and taxes included?
No. Subtract annual fees from the expected return (8% with a 1% fee becomes 7%) and check the tax rules for your account type.
Privacy
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