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FinCalc India

Compound Interest Calculator

Compound interest is interest on the principal plus all previously earned interest. Over long periods it produces dramatically more than simple interest — the 'snowball' effect that drives long-term investing.

Enter the principal, rate, period and how often interest is compounded.

Assumptions used
  • A constant rate over the whole period.
  • No withdrawals, fees or tax.

Enter your details

₹
11,00,00,00,000
%
140
years
150

Results

Compound Interest

₹1,59,374

Maturity Amount
₹2,59,374
  • Principal₹1.00 L(39%)
  • Interest₹1.59 L(61%)
Year-wise growth (10 rows)
YearAmountInterest So Far
1₹1,10,000₹10,000
2₹1,21,000₹21,000
3₹1,33,100₹33,100
4₹1,46,410₹46,410
5₹1,61,051₹61,051
6₹1,77,156₹77,156
7₹1,94,872₹94,872
8₹2,14,359₹1,14,359
9₹2,35,795₹1,35,795
10₹2,59,374₹1,59,374

Compound interest formula

A = P × (1 + R ÷ (100 × n))^(n × T)

  • P = principal
  • R = annual rate (%)
  • n = compounding periods per year
  • T = time in years

Compound interest = A − P. More frequent compounding gives a slightly higher amount.

Worked example

  1. ₹1,00,000 at 10% p.a. for 10 years, compounded annually.
  2. A = 1,00,000 × (1.10)^10 ≈ ₹2,59,374.
  3. Compound interest ≈ ₹1,59,374, versus only ₹1,00,000 with simple interest.

The power of compounding

  • Time is the biggest lever — the last few years contribute the most growth.
  • A higher rate compounds faster; even 1–2% extra return changes the outcome sharply over decades.
  • Frequent compounding helps, but far less than a longer horizon or a higher rate.
  • Reinvesting dividends and interest, rather than spending them, is what makes real portfolios compound.

Rule of 72

Divide 72 by the annual return to estimate the years to double your money. At 12% it is about 6 years; at 8%, about 9 years.

This calculator is for education and illustration only. Results are estimates based on the inputs and assumptions shown and are not financial, investment, tax or legal advice. Verify figures with your bank, a registered adviser or the relevant government department before acting.

Frequently asked questions

What is compound interest?

Interest calculated on the principal and on all interest added so far. Because each period's interest earns interest in later periods, the balance grows at an accelerating rate.

Which compounding frequency is best for an investor?

More frequent compounding gives a marginally higher return for the same nominal rate. The effect is small compared with the rate itself and the investment horizon.

How is compound interest different from simple interest?

Simple interest is charged only on the principal, so it grows linearly. Compound interest is charged on principal plus accumulated interest, so it grows faster over time.

What is the rule of 72?

A shortcut: years to double ≈ 72 ÷ annual return percent. It is an approximation that works well for typical rates between 4% and 15%.

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