Free compound interest calculator with periodic deposits, a year-by-year chart, and a full breakdown table. Model long-term savings, index funds, ETFs, stocks, or other assets using the compound interest formula.
This compound interest calculator helps you visualize how capital grows when returns are reinvested—from a regular savings plan to illustrative projections for index funds, ETFs, or diversified portfolios. Use it as an educational guide, not an exact market forecast.
You can save
1.819,40 €
saving 100,00 € monthly for 10 years
Initial Balance: 1.000,00 €
Periodic Deposits: 0,00 €
Total Interest: 819,40 €
Initial Balance
Periodic Deposits
Total Interest
| Year | Periodic Deposits | Total Contributions | Total Interest | Balance |
|---|---|---|---|---|
| 1 | 1.200,00 € | 1.000,00 € | 61,68 € | 1.061,68 € |
| 2 | 1.200,00 € | 1.000,00 € | 127,16 € | 1.127,16 € |
| 3 | 1.200,00 € | 1.000,00 € | 196,68 € | 1.196,68 € |
| 4 | 1.200,00 € | 1.000,00 € | 270,49 € | 1.270,49 € |
| 5 | 1.200,00 € | 1.000,00 € | 348,85 € | 1.348,85 € |
| 6 | 1.200,00 € | 1.000,00 € | 432,04 € | 1.432,04 € |
| 7 | 1.200,00 € | 1.000,00 € | 520,37 € | 1.520,37 € |
| 8 | 1.200,00 € | 1.000,00 € | 614,14 € | 1.614,14 € |
| 9 | 1.200,00 € | 1.000,00 € | 713,70 € | 1.713,70 € |
| 10 | 1.200,00 € | 1.000,00 € | 819,40 € | 1.819,40 € |
Enter your initial balance, recurring contribution, annual interest rate, and investment horizon. The calculator projects growth by reinvesting gains each period.
You can also choose whether contributions are made at the beginning or end of each period. That timing impacts the final outcome.
The core formula is Cn = C0 (1 + i)^n. With recurring contributions, each deposit is added over time and compounded based on the selected frequency.
You can explore different questions by changing only the inputs: starting balance, contribution, annual rate, and years.
1) How much will I accumulate over a given period? Enter what you have today, a contribution you can sustain, and a prudent rate. The year-by-year table and chart show how much comes from deposits versus compound growth.
2) How many years might it take to reach a goal? Adjust the duration until the final balance approaches your target (home, emergency fund, retirement). Compare a few return assumptions to see a plausible range of timelines.
3) What monthly contribution would move me toward my goal? Keep the timeline and rate fixed, then try different periodic deposit amounts until the final balance matches what you want to accumulate.
4) What annual return would be needed (approximately)? With starting balance, contributions, and timeline fixed, raise or lower the rate until the result matches your goal. This calibrates expectations—it does not promise a market return.
With compounding, each period’s return is calculated on a larger balance than the previous one (initial capital plus interest already earned). That is why, with the same nominal rate, longer time horizons and reinvested returns can accelerate growth in absolute terms.
Compound growth can support many long-term savings and investing approaches, such as funds, ETFs, stocks, and other assets. Consistency and a time horizon that fits your risk profile matter most.
Periodic compounding is the same mathematical idea across products, as long as returns accumulate over time and you stay invested according to liquidity needs and risk tolerance.
The longer the horizon, the more compounding periods you stack and the more interest can contribute to the total versus net contributions. Projections over 10, 20, or 30 years often show a steeper finish: that is math and discipline, not magic.
Monwey provides this compound interest calculator for educational purposes. It is not financial, tax, or investment advice. Markets fluctuate; fees and taxes can change real outcomes, and a fixed interest rate is a simplification. Speak with a professional for consequential decisions.
Beginning-of-period contributions generally produce higher results, since each deposit compounds for longer.
Choose the one that matches your cashflow. Monthly is often simplest for salaried income. Consistency matters most.
No. It is an educational projection based on assumptions, not a guarantee of actual market performance.
With simple interest, returns are calculated only on the original principal. With compound interest, interest is added to principal and earns returns in later periods—so with the same nominal rate, the long-term outcome is usually higher.
This tool models saving and investing with periodic contributions. Mortgages and loans use amortization schedules, variable rates, and different fees—use a dedicated loan simulator for payments and outstanding principal.
More contributions per year (with the same annual total) can put money to work earlier within each year, which can slightly change the outcome versus a single annual deposit. The practical difference depends on the rate and horizon.
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