The same starting numbers, three different outcomes
₹1,00,000 at 8% per annum for 10 years: simple interest gives exactly ₹80,000 in interest. Monthly compound interest gives ₹1,21,964.02. Daily compound interest gives ₹1,22,534.58 — both compound versions earn more than 50% extra compared to simple interest, for the exact same principal, rate, and duration.
Why the gap grows over time
Simple interest scales in a straight line — 10 years of interest is exactly 10/3 times 3 years of interest, no more. Compound interest scales exponentially — each year's interest gets added to the balance and starts earning its own interest, so the growth curve steepens the longer the money is left invested. A short holding period barely shows this difference; a long one shows it dramatically.
Why compounding frequency matters far less than compounding itself
Switching from monthly to daily compounding at 10 years only adds ₹570.56 — a small refinement. But switching from no compounding at all (simple interest) to any regular compounding adds over ₹40,000 to the interest earned on the same money. Whether interest compounds is a far bigger factor than exactly how often it compounds.
The practical takeaway
For any interest-bearing investment held for more than a few years, whether it's simple or compound interest matters enormously — checking which one applies before comparing two loan or deposit offers with the same quoted rate is essential, since a "simple interest" offer at the same rate as a compounding one will always underperform it over time.