Compound Interest Calculator
Simulate the growth of an investment over time with compound interest. Enter the initial amount, monthly contribution and interest rate — see the evolution chart and year-by-year table.
Investment Parameters
Investment Evolution Over Time
Yearly Details
| Year | Contributions | Interest Year | Total Invested | Total Value |
|---|
Rule of 72
Quickly estimate how long it takes to double your investment
The Rule of 72 is a simple formula: 72 / interest rate = years to double.
| Interest Rate | Doubles in | Interest Rate | Doubles in |
|---|---|---|---|
| 2% | 36 ani | 8% | 9 ani |
| 4% | 18 ani | 10% | 7,2 ani |
| 6% | 12 ani | 12% | 6 ani |
About Compound Interest
What is compound interest? Compound interest means that the interest earned is added to the initial capital and itself generates interest. It is the most powerful mechanism for long-term investment growth — Albert Einstein called it the "eighth wonder of the world".
Formula: A = P(1 + r/n)nt + PMT × [((1 + r/n)nt - 1) / (r/n)]
- P = initial amount (principal)
- r = annual interest rate (in decimal form)
- n = number of compounding periods per year (12 = monthly, 4 = quarterly, 1 = annual)
- t = duration in years
- PMT = monthly contribution
Monthly vs annual compounding: The more frequent the compounding, the higher the effective yield. At a 7% interest rate, monthly compounding generates an effective yield of 7.23%, compared to 7% with annual compounding.
Interest tax in Romania: Income from bank deposit interest is subject to a tax of 10%, withheld at source by the bank. Activate the "With 10% tax" option to see the fiscal impact.
Tips:
Investment Scenarios
Annual Interest Rate
Effective Annual Yield
Depending on compounding frequency
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