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Compound Interest
Compound Interest Calculator projects what a principal grows to when interest compounds, using the standard formula and the compounding frequency you choose — monthly by default. It reports the final balance and the interest earned separately.
How to use Compound Interest
- Enter the principal, the annual rate, the term in years and the compounding frequency.
- Calculate to see the final balance.
- Read the interest earned figure to see how much of the growth came from compounding.
Where Compound Interest is useful
- Projecting a savings account or fixed deposit.
- Showing why monthly compounding beats annual over a long term.
- Comparing a savings rate against expected inflation.
Formats, algorithms and limits
Growth follows A = P(1 + r/n)^(nt), where n is the compounding periods per year and t the term in years. Monthly (n = 12) is the usual bank convention. The model assumes a constant rate and no additional deposits or withdrawals, and it does not deduct tax or platform fees.
Troubleshooting and honest limits
- Extend the term rather than the rate to see why time matters more than a small rate difference early on.
- Keep the frequency consistent with your actual account: many savings products compound monthly but pay interest annually.
- For contributions added each month, this simple projection understates the result — model a growing principal instead.
Frequently asked questions
What is the difference between monthly and annual compounding?
Monthly compounding earns interest on interest sooner, so the same nominal rate produces a slightly higher final balance. The annual effective yield makes that difference explicit.
Does the term have to be whole years?
Fractions work: 2.5 years is accepted and converted into the right number of periods.
Does the tool account for inflation?
No. Subtract an expected inflation rate from the interest rate to see the real growth rate, or compare the result with a purchasing-power estimate.
Is this suitable for a formal financial projection?
Use it as a planning aid. A product's terms, tax treatment and fees belong in the number a decision rests on.
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Page written and reviewed by the FreeConvertio engineering team on 2026-10-14. Compound Interest runs entirely in your browser — no uploads, no account and no daily limits.