Compound Interest Calculator
Calculate the future value of your investment, total interest earned and compound growth over time.
Calculate Compound Interest
Future Value
Total Interest Earned
Principal Amount
Quick Summary
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods.
Enter your principal amount, annual interest rate, time period and compounding frequency to see how your investment grows.
How to Use This Calculator
- Enter the principal amount you're investing or saving.
- Enter the annual interest rate and the time period in years.
- Click Calculate to see the final amount and total interest earned.
What is Compound Interest?
Compound interest is the interest calculated on the initial principal amount as well as on the accumulated interest from previous periods. Unlike simple interest, which is calculated only on the principal, compound interest causes an investment or loan to grow at a faster rate over time.
This calculator estimates the future value of an investment based on the principal amount, annual interest rate, time period in years, and how frequently the interest is compounded.
Formula
A = P × (1 + r/n)^(n×t)
Where A = Future Value, P = Principal Amount, r = Annual Interest Rate (as a decimal), n = Number of Times Interest is Compounded Per Year, and t = Time Period in Years
Total Interest Earned = A − P
Worked Example
Principal Amount = ₹100,000
Annual Interest Rate = 8%
Time Period = 5 Years
Compounding Frequency = Annually (n = 1)
A = 100,000 × (1 + 0.08/1)^(1×5)
A ≈ ₹146,933
Total Interest Earned ≈ ₹46,933
Effect of Compounding Frequency
The more frequently interest is compounded, the faster an investment grows, since interest is added to the principal more often and starts earning interest sooner. Monthly compounding generally results in a higher future value than annual compounding for the same nominal interest rate.
Benefits
- Understand how investments grow over time.
- Compare different compounding frequencies.
- Plan long-term savings and investment goals.
- See the total interest earned versus principal.
- Make informed decisions about deposits and investments.
Practical Use Cases
- Comparing how a fixed deposit or recurring investment will grow over several years before committing.
- Understanding how much a delay in starting to save actually costs in lost compounding time.
Common Mistakes to Avoid
- Entering the annual rate but leaving the compounding frequency as annual when your investment actually compounds monthly or quarterly.
- Forgetting that 'time' should be in the same unit the rate is quoted in (years, almost always) — mixing months and years skews results heavily.
- Assuming the rate is guaranteed — market-linked investments show a probable rate, not a fixed one like a bank deposit.
Frequently Asked Questions
Simple interest is calculated only on the original principal amount, while compound interest is calculated on the principal plus any interest already earned, leading to faster growth over time.
A higher compounding frequency, such as monthly instead of annually, results in slightly higher returns because interest is added to the principal more often, allowing it to earn additional interest sooner.
This calculator is designed to estimate investment growth. For loan repayments with fixed monthly installments, an EMI calculator is more appropriate.