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Compound Interest Calculator

Estimate future value from a lump sum investment.

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Estimate future value from a lump sum investment. This dedicated page is built for fast, clean calculations and search visibility.

Enter your values, click calculate, and see the result instantly. The page uses a simple, focused layout to improve usability on mobile and desktop.

How to use this calculator

  1. Open the compound interest calculator page.
  2. Enter the required values in the form fields.
  3. Click Calculate to see the result and breakdown.
  4. Use the related links to explore similar tools.
Results are estimates. For lending, taxes, trading, nutrition, or medical decisions, verify with a qualified professional.

Compound Interest Calculator

Estimate future value from a lump sum investment.

Result
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    How compound interest works

    Compound interest means you earn returns not just on your original principal, but on all the interest you've already accumulated. This "interest on interest" effect is what makes long-term investing powerful — small differences in rate or time create enormous differences in outcome.

    The formula is FV = P × (1 + r/n)nt, where P is principal, r is the annual rate as a decimal, n is compounding frequency per year, and t is years. Monthly compounding (n=12) gives a slightly higher result than annual (n=1) because interest is added to principal more frequently.

    What compounding frequency actually changes

    • Annual (n=1): Used by many bonds and savings accounts. Simplest to track.
    • Monthly (n=12): Standard for most mutual funds and bank FDs in India. At 12% annual rate, monthly compounding gives an effective annual rate of ~12.68%.
    • Daily (n=365): Common in US high-yield savings accounts. The difference vs. monthly is usually under 0.1%.

    The biggest levers are rate and time. Doubling your rate is powerful, but starting 10 years earlier can easily outperform a 2% rate advantage started late. At 12%, ₹1 lakh grows 9× in 20 years but only 3.1× in 10 years — the second decade adds more than the first.

    Frequently asked questions

    What is the difference between simple and compound interest?â–¼
    Simple interest is calculated only on the original principal. Compound interest is calculated on principal plus all previously earned interest. Over long periods, the difference is dramatic — at 10% over 30 years, ₹1 lakh grows to ₹3 lakh with simple interest but over ₹17 lakh with annual compounding.
    How does the Rule of 72 relate to this calculator?â–¼
    The Rule of 72 is a shortcut: divide 72 by your annual rate to estimate years to double your money. At 12% annual rate, 72/12 = 6 years to double. This calculator gives you the precise figure, but the Rule of 72 is useful for quick mental math when comparing investment options.
    Should I use monthly or annual compounding for mutual fund estimates?â–¼
    Use monthly compounding (n=12) for most Indian mutual fund SIP estimates. Direct-plan equity funds typically reinvest gains on a daily basis, but monthly is a close and commonly accepted approximation for planning purposes.
    Why does starting early matter so much?â–¼
    Because the growth is exponential, not linear. At 12%, every rupee invested at age 25 is worth about ₹30 at age 65. Every rupee invested at age 35 is worth only about ₹9. The first 10 years triple the final outcome, which no amount of later investing can fully replace.