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Compound Interest Calculator

Discover the true power of compounding. See how frequently compounding makes a massive difference to your final wealth — and why starting early beats investing more.

📚 Understand This Calculator

Compound interest: the snowball that grows itself

Simple interest is like a tree that drops the same number of fruits every year. Compound interest is like a tree that drops fruits, but those fruits grow into new trees that also drop fruits. Each year, you're earning interest on your original money and on all the interest you already earned. Over decades, this creates the wealth snowball that Warren Buffett called "the eighth wonder of the world."

🇮🇳 Real-Life Example

Priya puts ₹1,00,000 in a scheme for 10 years:

📌 Simple interest at 8%: She earns ₹8,000 every year, period. After 10 years: ₹1,80,000.

📌 Compound interest at 8% (annual): In Year 1 she earns ₹8,000. In Year 2 she earns 8% on ₹1,08,000 = ₹8,640. This grows each year. After 10 years: ₹2,15,892.

📌 Compound interest at 8% (monthly): Same rate, but compounded 12 times a year. After 10 years: ₹2,21,964.

The difference between simple and monthly compound: ₹41,964 — all free money, zero extra effort.

💡 The Key Insight

Mutual fund NAVs compound every single trading day. This is why a 12% annual return in equity feels modest for the first 5 years but explosive by year 20. The math doesn't change — only time does. Starting 5 years earlier can mean ₹30–50 lakh more at retirement, even with the same monthly SIP amount.

⚠️ Common Mistake

Comparing FD interest with mutual fund returns without accounting for compounding frequency. Many FDs advertise 7.5% but compound quarterly — the effective annual yield is 7.71%. Always look at the effective annual rate (EAR), not the stated rate.

🔁 Investment Details
Your initial one-time investment.
Expected annual return (e.g. 12 for equity funds).
How often interest is added to your principal.
🔁

Enter your investment details

We'll show you the compounding effect, interest earned, and year-by-year growth.

The Formula

A = P × (1 + r/n)^(n×t)
Where

A = Final amount (what you get back)

P = Principal (your initial investment)

r = Annual interest rate (as a decimal, e.g. 12% = 0.12)

n = Compounding frequency per year (12 for monthly)

t = Time in years

Frequently Asked Questions

Why does monthly compounding give more than annual compounding?
With monthly compounding, interest is calculated and added 12 times a year. Each month's interest then earns interest in the following months. Annual compounding only adds interest once, missing 11 rounds of "interest on interest." Over 15–20 years, this difference compounds into a significant amount.
Do mutual funds compound daily or monthly?
Mutual funds don't technically "compound" in the traditional sense — they grow via NAV appreciation. The NAV is updated daily, which means your returns are effectively compounded daily. For calculation purposes, monthly compounding is a good approximation for equity mutual funds.
What is the Rule of 72 and how does it relate to compound interest?
The Rule of 72 is a quick estimate of compounding. Divide 72 by your annual rate to get the approximate years to double your money. At 12% CAGR, your money doubles every 72/12 = 6 years. It's derived from the compound interest formula but is a rough mental shortcut.
How does inflation affect compound interest?
To find your real return (inflation-adjusted), use the formula: Real Return = ((1 + nominal rate) / (1 + inflation rate)) − 1. At 12% returns and 6% inflation, your real return is approximately 5.66%, not 6%. Use our Inflation Calculator for an exact figure.

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