Compound Interest Calculator
Calculate compound interest on your investment with different compounding frequencies, year-wise breakdown and growth charts.
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What is a Compound Interest Calculator?
A compound interest calculator helps you determine the total amount and interest earned on an investment where interest is added to the principal at regular intervals. Unlike simple interest, compound interest earns "interest on interest," leading to exponential growth over time.
Compound Interest Formula
A = P × (1 + r/n)n×t
Where:
- A = Total Amount (Principal + Interest)
- P = Principal Amount
- r = Annual interest rate (in decimal)
- n = Number of times interest is compounded per year
- t = Time period in years
The compound interest (CI) itself is: CI = A − P
Compound Interest vs Simple Interest
- Simple Interest: Calculated only on the original principal. Formula: SI = P × r × t. Growth is linear.
- Compound Interest: Calculated on principal plus accumulated interest. Growth is exponential, resulting in significantly higher returns over longer periods.
- Key Difference: On ₹1,00,000 at 10% for 10 years — simple interest gives ₹1,00,000 interest, while compound interest (yearly) gives ₹1,59,374 interest.
Compound Interest Calculation Example
If you invest ₹1,00,000 at 8% annual interest for 5 years with quarterly compounding:
- Principal Amount: ₹1,00,000
- Compound Interest: ₹48,595
- Total Amount: ₹1,48,595
Compare this with simple interest for the same parameters: SI = ₹40,000. Compound interest earns you ₹8,595 more due to the effect of interest on interest.
Frequently Asked Questions
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Compound interest is the interest calculated on both the initial principal and the accumulated interest from previous periods. It causes your money to grow faster than simple interest because you earn interest on your interest.
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More frequent compounding results in higher returns. Monthly compounding yields more than quarterly, which yields more than yearly compounding. However, the difference becomes smaller as you move to very high frequencies.
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The Rule of 72 is a quick way to estimate how long it takes for an investment to double. Divide 72 by the annual interest rate. For example, at 8% interest, your money doubles in approximately 72 ÷ 8 = 9 years.
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For investments, compound interest is better because your returns grow exponentially. However, for loans, compound interest means you pay more over time. The longer the duration, the bigger the difference between compound and simple interest.
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Compound interest is used in bank savings accounts, fixed deposits, recurring deposits, mutual funds, PPF, and most loan products like home loans and credit cards. It is the fundamental principle behind wealth creation through investing.
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To maximize compound interest: start investing early to give your money more time to grow, choose instruments with higher compounding frequency, reinvest your returns instead of withdrawing them, and increase your principal regularly if possible.