Compound Interest Calculator
Calculate compound interest on your investments and savings with our free online Compound Interest Calculator. See how your money grows with the power of compounding. Supports monthly, quarterly, half-yearly, and yearly compounding frequencies used by Indian banks and financial institutions.
Calculate Compound Interest
Compound Interest Results
How Compound Interest Works
Compound interest is the interest calculated on both the initial principal and the accumulated interest from previous periods. This creates a snowball effect where your money grows exponentially over time—often called the "eighth wonder of the world" by Albert Einstein.
Compound Interest Formula
A = P(1 + r/n)nt
- A = Final Amount (Principal + Interest)
- P = Principal Amount (initial investment)
- r = Annual Interest Rate (in decimal form)
- n = Compounding Frequency per year
- t = Time Period (in years)
CI = A - P
Where CI is the Compound Interest earned
Understanding Compounding Frequency
The compounding frequency determines how often interest is calculated and added to your principal:
- Yearly (n=1): Interest added once per year
- Half-Yearly (n=2): Interest added twice per year
- Quarterly (n=4): Interest added four times per year (common for FDs)
- Monthly (n=12): Interest added every month (common for savings)
- Daily (n=365): Interest added every day (maximum compounding)
Higher compounding frequency results in higher returns because interest starts earning interest sooner.
The Power of Compounding
The real magic of compound interest is visible over long periods. A ₹1 lakh investment at 8% interest for 30 years grows to:
- Simple Interest: ₹3,40,000 (₹2,40,000 interest)
- Compound Interest (Yearly): ₹10,06,266 (₹9,06,266 interest)
- Compound Interest (Monthly): ₹10,93,573 (₹9,93,573 interest)
This demonstrates why starting early with investments is crucial—time is your greatest ally with compound interest.
Example Compound Interest Calculation
Let's calculate compound interest for a typical investment scenario:
Given Values
- Principal (P): ₹1,00,000
- Interest Rate (r): 8% per annum
- Time Period (t): 5 years
- Compounding: Monthly (n = 12)
Step-by-Step Calculation
-
Convert interest rate to decimal:
r = 8/100 = 0.08 -
Calculate rate per compounding period:
r/n = 0.08/12 = 0.00667 -
Calculate total compounding periods:
n × t = 12 × 5 = 60 -
Apply the formula:
A = 1,00,000 × (1 + 0.00667)60
A = 1,00,000 × (1.00667)60
A = 1,00,000 × 1.4898
A = ₹1,48,985 -
Calculate Compound Interest:
CI = A - P = 1,48,985 - 1,00,000
CI = ₹48,985
Result
- Total Amount: ₹1,48,985
- Compound Interest: ₹48,985
- Effective Annual Rate: 8.30%
Your ₹1 lakh grows by ₹48,985 in 5 years with monthly compounding—₹8,985 more than simple interest (₹40,000).
Quick Answers
What is compound interest?
Compound interest is interest calculated on the principal plus any interest already earned. Each period the base grows, so you earn interest on interest.
What is the compound interest formula?
Final amount = P × (1 + r/n)^(n×t), where P is principal, r is annual rate (decimal), n is compounding frequency per year, and t is time in years.
How does compounding frequency affect returns?
Higher frequency (e.g. monthly vs yearly) gives slightly higher returns because interest is added more often and starts earning sooner.
When is compound interest used in India?
FDs of 6 months or more, RDs, PPF, and most long-term investments and loans in India use compound interest.
Compound vs simple interest: which is higher?
For the same principal, rate, and time, compound interest is higher than simple interest because it grows on an increasing base.
Frequently Asked Questions
What is Compound Interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest (calculated only on principal), compound interest grows exponentially over time as you earn "interest on interest."
What is the difference between Compound Interest and Simple Interest?
Simple Interest is calculated only on the principal amount (SI = P×R×T/100), while Compound Interest is calculated on principal plus accumulated interest. For ₹1 lakh at 10% for 3 years: Simple Interest = ₹30,000, Compound Interest (annual) = ₹33,100. The difference increases significantly over longer periods.
Which compounding frequency gives the highest returns?
Daily compounding gives the highest returns, followed by monthly, quarterly, half-yearly, and yearly. However, the difference between monthly and daily compounding is minimal (about 0.02-0.05% effective rate difference). Most Indian banks compound quarterly for FDs and monthly for savings accounts.
What is Effective Annual Rate (EAR)?
Effective Annual Rate (EAR) is the actual annual return after accounting for compounding frequency. An 8% nominal rate compounded monthly has an EAR of 8.30%, meaning you effectively earn 8.30% per year. EAR helps compare investments with different compounding frequencies on an equal basis.
Where is Compound Interest used in India?
Compound interest is used in Fixed Deposits (FDs), Recurring Deposits (RDs), PPF, NSC, mutual fund returns, savings account interest, and most investment products. Home loans and personal loans also use compound interest (reducing balance method). Understanding compound interest is essential for financial planning in India.