What is a compound interest calculator?
A compound interest calculator projects how a lump-sum grows when interest is reinvested and earns further interest. The compounding frequency—yearly, half-yearly, quarterly, or monthly—changes the final amount even at the same annual rate.
Enter principal, rate, tenure, and compounding frequency. The tool shows principal, compound interest earned, and total maturity amount.
Why compounding frequency matters
More frequent compounding means interest is added to the balance sooner, so the next period's interest is calculated on a slightly larger base. The gap widens over longer tenures.
- Compare quarterly vs annual compounding on the same FD-style rate.
- Estimate long-term corpus for a one-time investment at an assumed CAGR.
- Contrast compound growth with flat simple interest on the same principal.
How does this calculator work?
Amount = Principal × (1 + r/n)^(n×t), where r is the annual rate as a decimal, n is compounding periods per year, and t is tenure in years.
A = P × (1 + r/n)^(n×t)
Where –
| A | Maturity amount |
|---|---|
| P | Principal |
| r | Annual rate as a decimal |
| n | Compounding periods per year |
| t | Tenure in years |
Example: ₹1,00,000 at 10% for 5 years, quarterly → A ≈ ₹1,63,862
Worked example
Deposit ₹1,00,000 at 10% per year for 5 years with quarterly compounding (n = 4). Maturity is about ₹1,63,862—roughly ₹63,862 above the principal. Annual compounding on the same inputs yields about ₹1,61,051, about ₹2,811 less.
How to use this compound interest calculator
Set principal, rate (p.a.), tenure, and compounding frequency. Results update instantly.
For bank FD math with quarterly compounding, see the FD calculator. For monthly investments, use the SIP calculator.
What this calculator does not include
Tax on interest, periodic deposits or withdrawals, and variable rates are not modeled. One lump sum and a constant rate are assumed.
Frequently asked questions
Is compound interest the same as CAGR?
Related but not identical. This tool applies a stated annual rate with a chosen compounding frequency. CAGR is the smoothed annual rate between two values over a period.
Which compounding frequency should I pick?
Match your product: Indian bank FDs typically compound quarterly. Mutual fund growth is often quoted as CAGR without discrete compounding periods.
Are results guaranteed?
No. Figures are estimates from your inputs. Market-linked investments do not grow at a fixed rate.