Compound returns calculator
Compounding is the closest thing investing has to magic. Drop your numbers in below and watch what happens.
The math: each year, your balance grows by your assumed return, then your monthly contributions are added on top. The curve is exponential — the last few years move more than the first ten combined.
Long-run S&P 500 average is ~10%. Conservative estimate: 7%.
Show year-by-year breakdown
| Year | Contributed | Growth | Balance |
|---|---|---|---|
| 1 | $16,000 | $1,055 | $17,055 |
| 2 | $22,000 | $2,695 | $24,695 |
| 3 | $28,000 | $4,970 | $32,970 |
| 4 | $34,000 | $7,932 | $41,932 |
| 5 | $40,000 | $11,637 | $51,637 |
| 6 | $46,000 | $16,148 | $62,148 |
| 7 | $52,000 | $21,531 | $73,531 |
| 8 | $58,000 | $27,859 | $85,859 |
| 9 | $64,000 | $35,210 | $99,210 |
| 10 | $70,000 | $43,669 | $113,669 |
| 11 | $76,000 | $53,329 | $129,329 |
| 12 | $82,000 | $64,288 | $146,288 |
| 13 | $88,000 | $76,655 | $164,655 |
| 14 | $94,000 | $90,546 | $184,546 |
| 15 | $100,000 | $106,088 | $206,088 |
| 16 | $106,000 | $123,419 | $229,419 |
| 17 | $112,000 | $142,685 | $254,685 |
| 18 | $118,000 | $164,049 | $282,049 |
| 19 | $124,000 | $187,684 | $311,684 |
| 20 | $130,000 | $213,778 | $343,778 |
| 21 | $136,000 | $242,537 | $378,537 |
| 22 | $142,000 | $274,180 | $416,180 |
| 23 | $148,000 | $308,948 | $456,948 |
| 24 | $154,000 | $347,099 | $501,099 |
| 25 | $160,000 | $388,915 | $548,915 |
| 26 | $166,000 | $434,700 | $600,700 |
| 27 | $172,000 | $484,782 | $656,782 |
| 28 | $178,000 | $539,520 | $717,520 |
| 29 | $184,000 | $599,299 | $783,299 |
| 30 | $190,000 | $664,537 | $854,537 |
A few things worth noticing
Time matters more than rate. Compare 30 years at 7% vs. 25 years at 9%. The longer window almost always wins. The single biggest lever you control is starting now.
Contributions compound too. A $500/month contribution feels small. Over 30 years at 8%, it's worth roughly $750,000. The first ten years feel slow. Then it gets weird, fast.
Returns are noisy.The market doesn't deliver a clean 8% every year — it delivers +20%, then +5%, then -15%, then +25%. The average is what matters over decades. The volatility is what you have to ignore in the meantime.
Costs compound too. Cut your assumed return by 1% and re-run. The difference at year 30 is usually a quarter to a third of the ending balance. Whether that 1% goes to fees, expense ratios, or trading costs, the math doesn’t care. The math only cares about the net number you actually compound at.
Now imagine those numbers on a portfolio that beat the S&P.
Our model portfolios are time-tested over decades against the S&P 500. See the full record.