Compound Interest Calculator

What is Compound Interest?

Compound interest is the interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest which is computed only on the original principal, compound interest allows your money to grow faster because you earn interest on your interest. This concept is often called the "eighth wonder of the world" and is the foundation of long-term wealth creation in India.

Compound Interest Formula

The formula for compound interest is: A = P(1 + r/n)^(nt), where:

A = Maturity Amount (future value), P = Principal (initial investment), r = Annual interest rate (in decimal), n = Number of times interest is compounded per year, t = Time period in years.

The total interest earned is calculated as: Interest = A - P.

Compound Interest vs Simple Interest

Simple interest is calculated only on the original principal using the formula SI = P x R x T / 100. With compound interest, the interest earned in each period is added to the principal, so you earn interest on a growing balance. Over longer time periods, compound interest generates significantly higher returns than simple interest. For example, Rs. 1,00,000 at 10% for 10 years gives Rs. 1,00,000 as simple interest but Rs. 1,59,374 as compound interest (compounded annually).

Rule of 72

The Rule of 72 is a quick way to estimate how long it takes to double your money with compound interest. Simply divide 72 by the annual interest rate. For example, at 8% interest, your money doubles in approximately 72/8 = 9 years. This rule is a useful shortcut for financial planning and comparing different investment options.

Frequently Asked Questions

Which compounding frequency gives the best returns?

Monthly compounding gives higher returns than quarterly, half-yearly or yearly compounding because interest is added to the principal more frequently, leading to a higher effective interest rate.

Where is compound interest used in India?

Compound interest is used in fixed deposits, recurring deposits, PPF, mutual funds, savings accounts and most bank loan calculations. Understanding compound interest helps you make better investment decisions.

Is compound interest better for investments or loans?

Compound interest benefits investors as their money grows faster. However, for loans, compound interest means you pay more over time. It is always advisable to invest early and repay loans quickly to take advantage of compounding.