compound interest with monthly contributions

Compound interest with monthly contributions

This landing exists because meaningful wealth growth rarely comes only from the initial lump sum; it usually comes from time plus contribution discipline.

⚠️ Educational simulation with monthly compounding. It does not replace portfolio advice, suitability review or net return calculations with real taxes and fees.

Initial investment

Monthly contribution

Interest rate

% a.m.

Duration

Meses

Annual inflationUsed to estimate the inflation-adjusted purchasing power of the final balance

% a.a.

Compare with benchmark

Result

Final balance

R$384,883.15

Total investedR$145,000.00

Accumulated returnsR$239,883.15

ROI165.4%

Real valueR$198,876.99

Mathematical simulation with monthly compounding and recurring contributions. It does not include income tax, IOF, administration fees, custody fees or slippage.

Portfolio growth

Year	Invested	Balance	Returns	Real value
1	R$19,000.00	R$20,594.24	R$1,594.24	R$19,707.40
2	R$28,000.00	R$32,391.02	R$4,391.02	R$29,661.43
3	R$37,000.00	R$45,526.85	R$8,526.85	R$39,895.03
4	R$46,000.00	R$60,153.73	R$14,153.73	R$50,442.60
5	R$55,000.00	R$76,440.90	R$21,440.90	R$61,340.08
6	R$64,000.00	R$94,576.82	R$30,576.82	R$72,625.14
7	R$73,000.00	R$114,771.35	R$41,771.35	R$84,337.25
8	R$82,000.00	R$137,258.15	R$55,258.15	R$96,517.89
9	R$91,000.00	R$162,297.41	R$71,297.41	R$109,210.65
10	R$100,000.00	R$190,178.88	R$90,178.88	R$122,461.45
11	R$109,000.00	R$221,225.16	R$112,225.16	R$136,318.67
12	R$118,000.00	R$255,795.50	R$137,795.50	R$150,833.36
13	R$127,000.00	R$294,289.90	R$167,289.90	R$166,059.45
14	R$136,000.00	R$337,153.79	R$201,153.79	R$182,053.90
15	R$145,000.00	R$384,883.15	R$239,883.15	R$198,876.99

Local browser-based simulation. This is not investment advice.

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Why contributions matter so much

Monthly contributions expand the base that continues to compound every period, accelerating the effect of growth.
Over long horizons, contribution consistency can explain more of the outcome than chasing tiny rate differences.

Useful readings

Recurring contribution

Input: R$ 10.000 + R$ 750/mês
Expected output: Curva de crescimento mais inclinada com o tempo

Good visualization for long-term planning.

No contributions

Input: Mesmo principal e mesma taxa
Expected output: Diferença relevante no saldo final

Helps measure the weight of discipline.

Full tool FAQ

Does the calculator model monthly contributions with compound growth?

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.

What is the benefit of switching between monthly and annual rate input?

Why compare the scenario against a benchmark?

What does real value mean here?

If I choose 18 months, does the new version keep the exact duration?

Does this calculator already deduct investment taxes?

Can I use it for pensions, ETFs or emergency fund projections?

Is a compound-interest simulation a forecast?

Frequently asked questions

Do smaller contributions still matter?

Yes. Over the long run, consistency is often much more powerful than it appears in a short-term glance.

Is it better to contribute more or seek a higher rate?

It depends on the scenario, and this page helps compare the relative weight of each variable.