What is Compound Interest?

There's a reason compound interest gets called the "eighth wonder of the world." It's interest on interest — your earnings get added to the principal, and then the next period's interest is calculated on that larger number. Over time, this creates a snowball effect. The longer it runs, the more dramatic the growth becomes. It's the core mechanic behind why long-term investing works so well.

How This Calculator Helps You See the Future

It's one thing to understand compounding conceptually. It's another to see what it actually does to a specific number over a specific time period.

• Enter an initial investment — a fixed deposit, a stock purchase, anything really — and see what it might grow to over several years at a given return rate.
• The compounding frequency slider is worth playing with. Monthly compounding produces slightly better results than annual compounding at the same nominal rate, and the calculator shows you exactly how much that difference amounts to over your time horizon.
• The pie chart makes the most important point visually: after many years, the interest earned can easily exceed the money you originally invested. That's the whole argument for starting early.

Key Takeaway

Time is the ingredient that makes compounding work. The same investment held for 30 years doesn't just earn twice as much as one held for 15 years — it often earns four or five times as much, because the interest itself has had years to compound. This calculator is a good way to feel that difference in your gut, not just understand it in theory.