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Compound Interest Calculator

Calculate how any lump sum grows with compound interest. Choose compounding frequency and see the magic of interest earning interest over time.

Investment Details
Currency
Principal Amount$10,000
$
10010,00,000
Annual Interest Rate8%
%
0.1%50%
Time Period (Years)10 Years
Yr
1 Yr50 Yr
Compounding Frequency
Your Result

Fill in the details and
your result appears here.

Final Amount
$
Principal
Total Interest
Total Amount
Effective Annual Rate
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Did You Know?
The 72 Rule
At 8% annual return, your money doubles every 9 years (72 ÷ 8). At 12%, it doubles every 6 years. This simple rule shows why rate matters more than frequency.

How to use this calculator

1

Enter principal

The initial amount you are investing or depositing.

2

Set interest rate

Annual rate offered by the bank or investment product.

3

Set time period

Number of years the money stays invested.

4

Choose compounding frequency

Bank FDs are usually quarterly. Savings accounts are monthly or daily.

The formula explained

A = P × (1 + r/n)^(n×t)

P = Principal   r = Annual rate ÷ 100   n = Compounding periods per year   t = Years

More frequent compounding = slightly higher returns. Daily compounding on 8% gives an effective annual rate of 8.328% vs exactly 8% for annual compounding.

Frequently Asked Questions

What is compound interest?

Compound interest means you earn interest on your interest, not just on the principal. Over long periods this creates exponential growth — the core of the Rule of 72.

What is the Rule of 72?

Divide 72 by the interest rate to find how many years it takes to double your money. At 8%, 72 ÷ 8 = 9 years to double.

Which compounding frequency is best?

More frequent = slightly better. But the difference between monthly and daily is tiny. The rate and time period matter far more.

How is compound interest different from SIP?

Compound interest is for a one-time lump sum. SIP is for regular monthly investments. Both use compounding, but SIP builds corpus through instalments.

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