Compound Interest Calculator

What is Compound Interest Calculator?

The Compound Interest Calculator shows how money grows when interest earns interest. You can compare different compounding frequencies (daily, monthly, quarterly, annually) to see how each affects your final returns.

How to Calculate Compound Interest

1. Enter the principal amount
2. Enter the annual interest rate
3. Select the compounding frequency (monthly, quarterly, annually)
4. Enter the time period in years
5. Click Calculate to see final amount, total compound interest, and growth chart

How Compound Interest Calculator is Calculated

A = P × (1 + r/n)^(n×t), where A = final amount, P = principal, r = annual interest rate as a decimal, n = number of times interest compounds per year, t = time in years. Compound Interest = A − P.

Worked Example

₹1,00,000 at 8% for 10 years with quarterly compounding: A = 1,00,000 × (1 + 0.08/4)^40 = ₹2,20,804. CI = ₹1,20,804. Compare with simple interest: ₹80,000 — compounding earned ₹40,804 extra.

Common Use Cases

• Understanding how compounding grows wealth
• Comparing bank FD compounding options
• Teaching the Rule of 72
• Investment growth projections

Common Mistakes to Avoid

• Confusing the annual rate with the rate per compounding period — an 8% annual rate compounds as 2% per quarter, not 8%.
• Assuming more frequent compounding always makes a huge difference — the marginal gain from daily vs monthly compounding is small for typical rates.
• Using nominal rate instead of effective annual rate when comparing investments with different compounding frequencies.
• Forgetting that Rule of 72 gives only an approximation — 72 / rate gives the approximate years to double, but is less accurate above 15%.

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