compound interest with monthly contributions
The real question is not only how much it grows, it is how much of the final result came from the money you added month after month, not from the rate itself.
Interest already overtakes contributions around the midpoint of the horizon, because the accumulated balance starts generating more monthly return than the fixed contribution itself.
The R$ 334,717.10 gap versus the contribution scenario shows that, here, monthly discipline weighed more than 15 years of compounding on the initial capital alone.
Halving the monthly contribution does not halve the final balance, because the initial capital and the earliest months of growth remain intact in the calculation base.
Yes. The tool compounds the balance month by month and adds the recurring contribution every period, which makes it much more useful for real accumulation planning than a simple lump-sum-only model.
In this 180-month simulation, yes: the scenario with contributions ends at R$ 384,883.15 versus R$ 50,166.05 with no contribution at all, a gap of over R$ 330 thousand caused only by the recurring contribution.
It depends on the horizon: over long terms like 180 months, raising the contribution has an immediate, predictable effect on the balance, while gaining a few tenths of rate takes time to compound and is harder to sustain.
Yes. Each R$ 750 contribution becomes part of next month balance and earns 0.9% again, alongside the initial capital and previous contributions: that is why accumulated interest (R$ 239,883.15) ends up exceeding the total invested (R$ 145,000.00).
⚠️ Educational simulation with monthly compounding. It does not replace portfolio advice, suitability review or net return calculations with real taxes and fees.
Mathematical simulation with monthly compounding and recurring contributions. It does not include income tax, IOF, administration fees, custody fees or slippage.
Portfolio growth
Breakdown
| Year | Invested | Return this year | Balance | Real value |
|---|---|---|---|---|
| 1 | R$19,000.00 | R$1,594.24 | R$20,594.24 | R$19,707.40 |
| 2 | R$28,000.00 | R$2,796.78 | R$32,391.02 | R$29,661.43 |
| 3 | R$37,000.00 | R$4,135.83 | R$45,526.85 | R$39,895.03 |
| 4 | R$46,000.00 | R$5,626.88 | R$60,153.73 | R$50,442.60 |
| 5 | R$55,000.00 | R$7,287.17 | R$76,440.90 | R$61,340.08 |
| 6 | R$64,000.00 | R$9,135.92 | R$94,576.82 | R$72,625.14 |
| 7 | R$73,000.00 | R$11,194.52 | R$114,771.35 | R$84,337.25 |
| 8 | R$82,000.00 | R$13,486.80 | R$137,258.15 | R$96,517.89 |
| 9 | R$91,000.00 | R$16,039.27 | R$162,297.41 | R$109,210.65 |
| 10 | R$100,000.00 | R$18,881.47 | R$190,178.88 | R$122,461.45 |
| 11 | R$109,000.00 | R$22,046.28 | R$221,225.16 | R$136,318.67 |
| 12 | R$118,000.00 | R$25,570.34 | R$255,795.50 | R$150,833.36 |
| 13 | R$127,000.00 | R$29,494.40 | R$294,289.90 | R$166,059.45 |
| 14 | R$136,000.00 | R$33,863.89 | R$337,153.79 | R$182,053.90 |
| 15 | R$145,000.00 | R$38,729.36 | R$384,883.15 | R$198,876.99 |
Return this year = interest generated within that year on the accumulated balance.
Local browser-based simulation. This is not investment advice.