What is Compound Interest?
Compound interest is interest calculated on the principal and on the interest already earned. Each year’s interest is added to your balance, and the next year’s interest is calculated on that larger amount.
This “interest on interest” makes your money grow faster over time than simple interest at the same rate, and the effect gets stronger the longer you stay invested.
Compound interest is used for fixed deposits, savings accounts, most investments and many loans.
Fun fact
At 10% compound interest, your money doubles in a little over 7 years, compared with 10 years at 10% simple interest.
What is a Compound Interest Calculator?
A compound interest calculator works out how much your money will grow to, and how much of that is interest, based on the principal, the rate of interest and the time period. Interest is compounded yearly.
Why you should use a Compound Interest Calculator?
- Simplifies the process: Compounding over many years is hard to work out by hand. The calculator does it in seconds.
- See the power of time: Change the time period to see how much more your money grows the longer it stays invested.
- Helps in comparison: Compare different rates and time periods before you invest.
How Does a Compound Interest Calculator Work?
The compound interest calculator works on the following inputs:
- Principal Amount (P): The amount you invest.
- Rate of Interest (R): The yearly rate of interest.
- Time Period (T): Number of years.
The calculator relies on the following formula:
Total Amount = P × (1 + R ÷ 100)^T
- P
- Principal Amount
- R
- Rate of Interest per year
- T
- Time Period in years
The total interest is the total amount minus the principal.
Formula to Calculate Compound Interest with an Example
Consider an example for a better understanding.
- Principal Amount: ₹1,00,000
- Rate of Interest: 10% per annum
- Time Period: 5 years
Using the formula:
A = 1,00,000 × (1 + 0.10)^5
After calculation, the total amount is ₹1,61,051, of which ₹61,051 is interest — ₹11,051 more than simple interest at the same rate.
What are the benefits of Compound Interest?
- Faster growth: Your interest earns interest, so your money grows faster than with simple interest.
- Rewards patience: The longer you stay invested, the bigger the effect of compounding.
- Builds wealth: Compounding is the main reason long-term investing can grow even small amounts into a large corpus.