Formula used
Subtracts each expense ratio from the same assumed gross return and compounds both net return assumptions for the selected period.
Example calculation
For a ₹5,00,000 lumpsum held for 15 years, assume both funds earn 12% a year before costs. An index-fund expense ratio of 0.2% gives an 11.8% net return assumption and about ₹26.64 lakh. An active-fund expense ratio of 1.5% gives a 10.5% net return assumption and about ₹22.36 lakh. The modelled difference is about ₹4.29 lakh from fees alone. These constant-return assumptions exclude tax, exit loads and tracking differences; they do not forecast either fund's actual performance.
This page isolates expense-ratio drag
The purpose is to answer a cost question, not a SIP-return question. Both fund routes use the same assumed gross return so the output shows the mathematical effect of recurring fund expenses over time.