Compound Interest Calculator – Calculate CI Instantly
Compound Interest
Total Amount
Principal Amount
What is Compound Interest?
Compound Interest (CI) is interest calculated on both the original principal and all previously accumulated interest. Each compounding period, the interest earned is added to the principal, so the next period earns interest on a larger amount. This creates an exponential growth effect — famously described by Albert Einstein as "the eighth wonder of the world."
Compound Interest Formula
A = P × (1 + r/n)^(n×t)
CI = A - P
P = Principal | r = Annual Rate ÷ 100 | n = Compounding frequency/year | t = Time in years
Here is a worked example:
- Principal: ₹1,00,000
- Interest Rate: 10% per annum
- Time Period: 5 years
- Compounding: Quarterly (n = 4)
A = 1,00,000 × (1 + 0.10/4)^(4×5)
A = 1,00,000 × (1.025)^20
Total Amount ≈ ₹1,63,862 | Compound Interest ≈ ₹63,862
Compounding Frequencies Explained
Annually (n = 1)
Interest is compounded once a year. The simplest frequency and gives the lowest effective yield for a given nominal rate.
Semi-annually (n = 2)
Interest is compounded every six months. Many bonds, debentures, and some savings schemes use this frequency.
Quarterly (n = 4)
Interest is compounded every three months. Most Indian bank FDs and RDs use quarterly compounding as their standard.
Monthly (n = 12)
Interest is compounded every month — the most frequent standard option. Gives the highest effective annual yield for the same nominal interest rate.
Simple Interest vs Compound Interest
For the same principal of ₹1,00,000 at 10% per annum over 5 years:
| Type | Interest Earned | Total Amount |
|---|---|---|
| Simple Interest | ₹50,000 | ₹1,50,000 |
| Compound Interest (Quarterly) | ₹63,862 | ₹1,63,862 |
Compound interest earns ₹13,862 more than simple interest on the same investment — a 27.7% higher return.
Where is Compound Interest Used?
- Fixed Deposits & RDs: Banks apply quarterly compounding on FDs and RDs, making compound interest the standard for all term deposits in India.
- Mutual Funds & SIPs: Returns in mutual funds grow through compounding — reinvested gains earn further returns, exponentially growing your wealth over time.
- PPF & Long-term Savings: The Public Provident Fund uses annual compounding. Over 15 years, the compounding effect becomes a powerful wealth multiplier.
- Loans & Credit Cards: Compounding works against borrowers — unpaid credit card balances compound monthly, which is why outstanding dues grow rapidly if left unpaid.
Frequently Asked Questions About Compound Interest Calculator
What is Compound Interest?
Compound Interest is interest calculated on both the original principal and all previously accumulated interest. Each period the earned interest is added back to the principal, so the next period earns interest on a growing balance.
What is the Compound Interest formula?
A = P × (1 + r/n)^(n×t), where P is the principal, r is the annual rate ÷ 100, n is the compounding frequency per year, and t is the time in years. Compound Interest = A - P.
What is the difference between Simple and Compound Interest?
In Simple Interest, the interest amount is identical every period because it is always calculated on the original principal. In Compound Interest, the interest grows each period because it is calculated on an ever-increasing balance — leading to substantially higher returns over long tenures.
Which compounding frequency gives the highest return?
Monthly compounding gives the highest return because interest is added to the principal 12 times per year, allowing every subsequent cycle to earn interest on a larger balance compared to quarterly, semi-annual, or annual compounding.
Where is Compound Interest used in real life?
Compound Interest is used in Fixed Deposits, Recurring Deposits, Mutual Funds, PPF, NPS, home loans, and credit cards. It is the foundation of virtually every modern financial product — working in your favour when you invest and against you when you borrow.
What is the Rule of 72 in compound interest?
The Rule of 72 is a quick mental shortcut: divide 72 by the annual interest rate to estimate how many years it takes to double your money. For example, at 9% per annum, your investment doubles in approximately 72 ÷ 9 = 8 years.
Is Calcon's Compound Interest Calculator free?
Yes, completely free — no sign-up, no download, no usage limit. Works on all devices including mobile.
Related Calculators
GST Calculator
Add or remove GST from any price instantly.
EMI Calculator
Calculate loan EMI with full amortization schedule.
SIP Calculator
Plan your mutual fund SIP investments easily.
PPF Calculator
Calculate PPF maturity amount and interest.
Pregnancy Due Date Calculator
Estimate your pregnancy due date easily.
FD Calculator
Calculate FD maturity amount and interest instantly.
RD Calculator
Calculate RD maturity amount and interest instantly.
Simple Interest Calculator
Calculate SI using the P × R × T / 100 formula.
Percentage Calculator
Calculate percentages and percentage change instantly.
Discount Calculator
Find sale price and discount % instantly.
