Free tool
See how much your money can grow — with monthly or yearly compounding and a regular monthly contribution.
Final balance
€40,387
×4 your moneyInvested
€10,000
Interest earned
+€30,387
Return
+303.9%
Compounding adds €16,387 over simple interest.
Now do it with your real numbers
TrackYour.finance reads your Google Sheet and projects your actual savings, goals and net worth — updated every time you add a transaction.
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| Year | Invested | Simple interest | Compound interest |
|---|---|---|---|
| Year 1 | €10,000 | €10,700 | €10,723 |
| Year 2 | €10,000 | €11,400 | €11,498 |
| Year 3 | €10,000 | €12,100 | €12,329 |
| Year 4 | €10,000 | €12,800 | €13,221 |
| Year 5 | €10,000 | €13,500 | €14,176 |
| Year 6 | €10,000 | €14,200 | €15,201 |
| Year 7 | €10,000 | €14,900 | €16,300 |
| Year 8 | €10,000 | €15,600 | €17,478 |
| Year 9 | €10,000 | €16,300 | €18,742 |
| Year 10 | €10,000 | €17,000 | €20,097 |
Compound interest is interest earned on your interest. Each period, the return is added to your balance, so the next period earns on a bigger amount. Over long horizons this snowball effect is what makes patient investing work.
Simple interest, by contrast, only ever pays on the money you put in. The dashed line in the chart shows that path — the gap between the two is what compounding adds.
With monthly compounding, an initial amount P at an annual rate r for t years grows to:
A = P · (1 + r/12)12t
and a monthly contribution C adds:
C · [(1 + r/12)12t − 1] / (r/12)
Enter your initial amount, the annual return you expect and the number of years. If you invest every month, add the monthly contribution. Choose monthly or yearly compounding — the results, chart and year-by-year table update instantly.
Broad index funds and ETFs have historically returned around 7–10% a year before inflation, high-yield savings accounts pay roughly 2–4%, and conservative portfolios sit around 3–5%. Past returns are no guarantee of future ones, so it helps to try several rates.
With monthly compounding, interest is added 12 times a year, so it starts earning sooner and ends slightly higher than yearly compounding. The difference is small each year but grows over long horizons.
No — results are gross. Taxes on gains and fund fees reduce the final amount, so treat the result as an upper bound and compare scenarios rather than relying on one exact figure.
Connect the Google Sheet where you already track your money to TrackYour.finance. It projects your real savings pace, goals and net worth, so you can see whether you are on track — not just in a calculator.
Stop recalculating by hand. Connect your Sheet and see your real trajectory, every day.
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