Compound Interest Calculator

Compound interest is often called the "eighth wonder of the world". Unlike simple interest, which is calculated only on the principal amount, compound interest is calculated on the principal plus the interest accumulated over previous periods. This "interest on interest" effect causes your wealth to grow exponentially rather than linearly.

Simple Interest: Returns are constant. If you invest $100 at 10%, you get $10 every year. After 10 years, you have $200.

Compound Interest: Returns grow. Year 1 you get $10. Year 2 you get $11 (10% of 110). Year 3 you get $12.1. After 10 years, you have ~$259.

Over long periods (20-30 years), compound interest can result in wealth that is 3x or 4x higher than simple interest.

How often interest is added matters. Our calculator supports:

• Annually: Interest added once a year.
• Semi-Annually: Twice a year.
• Quarterly: Four times a year.
• Monthly: Twelve times a year (Common for savings accounts).
• Daily: 365 times a year.

The more frequent the compounding, the higher the final return. For example, $1 Lakh at 10% for 1 year is $1.10 Lakh (Annually) vs $1.105 Lakh (Daily).

Want a quick mental math trick? The Rule of 72 estimates how long it takes to double your money.

`Years to Double = 72 / Interest Rate`

Example: At 12% return, your money doubles in 72/12 = 6 years. At 8%, it takes 9 years. Use our calculator to verify this rule!

1. Start Early: Time is the biggest factor in compounding. Starting 5 years earlier can double your retirement corpus.
2. Increase Frequency: Choose investments that compound quarterly or monthly if possible.
3. Reinvest Earnings: Never withdraw the interest; let it stay invested to earn more interest.

You can calculate future value with compound interest in Excel using the FV function.

Formula: `=FV(rate, nper, pmt, [pv], [type])`

• rate: Interest rate per period (Annual Rate / Frequency)
• nper: Total number of compounding periods (Years * Frequency)
• pmt: Periodic payment (0 for lumpsum only)
• pv: Present Value (Principal amount, negative)

Example:

$1 Lakh at 10% annually for 5 years:

`=FV(10%, 5, 0, -100000)`

This will return the maturity amount.

If you had a choice between receiving $1 Crore today or a single penny ($0.01) that doubles every day for 30 days, which would you choose?

• Option A: $1,00,00,000
• Option B: $0.01 doubling 30 times

Result: Option B would grow to over $53 Lakhs on Day 30 alone, and the total would be over $1 Crore! Wait, actually $0.01 * 2^29 is ~$53 Lakhs. Total sum is ~$1 Crore. It demonstrates the explosive power of compounding.