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What is Compound Interest?
Compound interest is the interest you earn on interest. When you invest or save money, your initial principal amount earns interest. In the next compounding period, you earn interest on both your initial principal AND the interest you just accumulated. Over time, this compounding effect creates a snowball effect, accelerating the growth of your savings exponentially.
Compounding Frequency Matters
How often your interest compounds has a massive impact on your final balance. The more frequently interest is compounded, the higher your maturity value will be. Common compounding frequencies include:
- Daily: Compounded 365 times a year.
- Monthly: Compounded 12 times a year.
- Quarterly: Compounded 4 times a year (standard for Indian Fixed Deposits).
- Half-Yearly: Compounded 2 times a year.
- Annually: Compounded once a year.
For example, if you invest ₹10,000 at a 10% annual interest rate for 5 years:
- Yearly Compounding: Yields ₹16,105
- Quarterly Compounding: Yields ₹16,386
- Monthly Compounding: Yields ₹16,453
The Formula Behind Compounding
The math formula used to compute compound interest is: A = P(1 + r/n)^(nt), where:
- A: Final Maturity Amount
- P: Principal Investment Amount
- r: Annual Interest Rate (as a decimal)
- n: Compounding frequency per year
- t: Time period in years
Calculate your growth instantly with our free Compound Interest Calculator which automatically constructs a year-by-year schedule breakdown for you.
Frequently Asked Questions
The Rule of 72 is a quick way to estimate how long it will take for your money to double under compound interest. Simply divide 72 by your annual interest rate. For example, at an 8% interest rate, your money will double in approximately 9 years (72 / 8).
Simple interest is only calculated on the initial principal amount. Compound interest is calculated on the principal plus any accumulated interest from previous periods.
If you owe money on a credit card, the interest compounding frequency works against you. Most credit card companies compound interest daily, meaning your debt grows faster than it would with monthly or annual compounding.