The Power of Compounding Frequencies Explained
Compound interest is interest calculated on the initial principal plus all accumulated interest from prior periods. Albert Einstein famously called it the eighth wonder of the world: he who understands it, earns it; he who doesn't, pays it.
The more frequently interest is calculated and added to the principal (daily vs annual), the higher the final maturity corpus will be due to continuous interest-on-interest accumulation.
Compounding Math Formula with Periodic Deposits
A = P × (1 + r / n)^(n × t) + PMT × [((1 + r / n)^(n × t) - 1) / (r / n)]
Where P is initial principal, r is annual interest rate (decimal), n is compounding frequency per year, t is tenure in years, and PMT is recurring contribution per period.
Impact of Compounding Frequency on ₹5,00,000 at 12% over 10 Years
| Compounding Frequency | Times / Year | Final Maturity Corpus | Effective Annual Rate (AER) |
|---|---|---|---|
| Annually | 1 | ₹15,52,924 | 12.00% |
| Semi-Annually | 2 | ₹16,03,568 | 12.36% |
| Quarterly | 4 | ₹16,31,019 | 12.55% |
| Monthly | 12 | ₹16,50,193 | 12.68% |
| Daily | 365 | ₹16,59,796 | 12.75% |
The Rule of 72: Mental Math for Doubling Money
The Rule of 72 is an accurate mental shortcut to estimate how many years it takes for an investment to double at a given compound interest rate:
Years to Double ≈ 72 / Annual Interest Rate (%)
- At 6% (Bank FD): 72 / 6 = 12 Years to double.
- At 12% (Nifty 50 Index SIP): 72 / 12 = 6 Years to double.
- At 18% (High Growth Small Cap): 72 / 18 = 4 Years to double.