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What $100 a month for 10 years becomes
Investing $100 a month is about $3.29 a day. Over 10 years you’d contribute $12,000 in total. What it turns into depends on the return:
| Average return | Balance after 10 years | Growth |
|---|---|---|
| 5% (conservative) | $15,528 | $3,528 |
| 7% (≈ stocks after inflation) | $17,308 | $5,308 |
| 8% (our default) | $18,295 | $6,295 |
| 10% (≈ S&P 500 long-run) | $20,484 | $8,484 |
At 8%, every dollar you put in becomes about 1.5 dollars. Over 10 years most of the result is still your own contributions; compounding needs 20+ years to really take over. The same $100 a month for 20 years would reach about $58,902 — more than double for double the time.
Year by year (8%)
| Year | You put in | Balance |
|---|---|---|
| 1 | $1,200 | $1,245 |
| 2 | $2,400 | $2,593 |
| 3 | $3,600 | $4,054 |
| 4 | $4,800 | $5,635 |
| 5 | $6,000 | $7,348 |
| 6 | $7,200 | $9,203 |
| 7 | $8,400 | $11,211 |
| 8 | $9,600 | $13,387 |
| 9 | $10,800 | $15,743 |
| 10 | $12,000 | $18,295 |
Assumes contributions at the end of each month, monthly compounding and a constant return; ignores taxes, fees and inflation. Educational estimates, not advice.
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Open calculator →Questions people ask
How much is $100 a month for 10 years?
You would contribute $12,000. At an 8% average annual return, compounded monthly, it grows to about $18,295; at 10% about $20,484; at 5% about $15,528.
Is 8% a realistic return for $100 a month?
It is close to the long-run average of a broad US stock index fund including dividends (about 10% before inflation, 7% after). Real returns swing widely year to year; use the calculator to test other rates.
What if I invest $100 a month for 20 years instead of 10?
At the same 8% average return it grows to about $58,902, from $24,000 contributed. The extra 10 years add about $40,607, because growth starts earning growth.
How long does $100 a month take to reach $1 million?
About 53 years at an 8% average annual return, starting from zero. Hypothetical, not guaranteed; real returns vary year to year.