Compound Interest

Compound interest is what happens when the returns you earn start earning their own returns. Put ₹10,000 into an investment earning 10% a year, and after one year you have ₹11,000. But in year two, you're not earning 10% on ₹10,000 anymore — you're earning it on ₹11,000. The gap between simple and compound growth looks small at first and enormous later.

This is why the order of your investing decisions matters less than the number of years you stay invested. ₹5,000 invested monthly for 30 years at 12% annual return grows to roughly ₹1.76 crore. Wait just 10 years to start, and investing the same amount for 20 years only gets you to about ₹50 lakh — less than a third, despite investing for two-thirds as many years.

The practical takeaway: the biggest lever you control isn't picking the perfect investment — it's starting now instead of later. A mediocre investment started today usually beats a great investment started in five years.

Compounding cuts both ways, though. Debt compounds too. A credit card balance at 36% annual interest grows just as relentlessly as an investment, which is exactly why paying off high-interest debt is often the single highest-return move available to you — see the Pay Off Debt vs Invest tool for the real math on your own numbers.