See what $100/month invested every month for 20 years could grow to, with the 5%, 7% and 10% return scenarios, the compound-growth formula and a year-by-year chart.
| Annual return | Future value | Total growth |
|---|---|---|
| 5% | $41,103 | $17,103 |
| 7% | $52,093 | $28,093 |
| 10% | $75,937 | $51,937 |
FV = PMT × [ ((1 + i)n − 1) ÷ i ], where PMT = $100, i = monthly rate (7%/12), n = 240 months.
Investing $100/month every month for 20 years means contributing $24,000 of your own money. At a 7% average annual return — roughly the long-run average of a diversified stock-market index fund after inflation is set aside — compounding turns that into about $52,093. The difference, $28,093, is investment growth: returns earning further returns. The earlier and longer you invest, the larger that growth share becomes, which is why starting monthly contributions young is so powerful. These figures assume a constant return and reinvested earnings; real markets fluctuate year to year, and taxes and fees reduce net returns. Use them as a planning illustration, then model your own numbers in the full calculator. Past performance does not guarantee future results.