The process where returns on an investment generate their own returns over time, creating exponential growth often called the "eighth wonder of the world."
Compounding is the process by which investment returns generate additional returns over time. Unlike simple interest (earned only on the principal), compound interest is earned on both the principal and accumulated interest, creating exponential growth. Albert Einstein reportedly called it "the eighth wonder of the world."
The mathematical power of compounding is best illustrated with Indian numbers. Rs 1 lakh invested at 12% annual return (close to long-term Indian equity CAGR): after 10 years = Rs 3.11 lakh, after 20 years = Rs 9.65 lakh, after 30 years = Rs 29.96 lakh. The investment grows nearly 30x in 30 years — but 20x of that growth happened in the last 10 years. This back-loaded nature of compounding is why starting early is so powerful.
In practical Indian investing, compounding works through several mechanisms. In SIPs (Systematic Investment Plans), monthly investments compound as returns generate further returns. In growth-option mutual funds, dividends are reinvested and compound within the fund. In stocks, companies that reinvest profits at high Return on Equity (ROE) — like Asian Paints (historically 25%+ ROE) or HDFC Bank — compound book value, which drives stock price appreciation.
The Rule of 72 is a useful shortcut: divide 72 by the annual return rate to estimate doubling time. At 12% returns (equity), money doubles every 6 years. At 7% (fixed deposits), every 10.3 years. At 15% (high-growth stocks), every 4.8 years. This simple calculation helps investors set realistic expectations and plan for long-term goals like retirement.
Three factors determine compounding outcomes: rate of return, time horizon, and consistency. Even small differences in return compound massively over time — Rs 10,000 monthly SIP at 12% grows to Rs 1 crore in about 20 years, but at 15% it reaches Rs 1.5 crore in the same period. This is why minimising costs (choosing low Expense Ratio funds, using direct plans) and staying invested through market cycles matters enormously. Every year out of the market is a lost compounding year that can never be recovered.
Formula
Future Value = Present Value x (1 + r)^n, where r = annual rate, n = years