Index funds and ETFs both track the same underlying index and are often described interchangeably — but the cheaper-looking option on paper isn't always the cheaper option in practice. Here's the real cost and convenience difference for an Indian investor deciding between the two.
What they actually have in common
Both index funds and ETFs passively track a benchmark like the Nifty 50 or Sensex, aiming to mirror the index's return rather than beat it through active stock-picking. Both charge a fund-management expense ratio, and both are meaningfully cheaper than actively managed equity funds. The difference is entirely in how you buy, hold, and exit them.
The expense ratio isn't the whole cost picture
| Index Fund | ETF | |
|---|---|---|
| Headline expense ratio (Direct plan) | ~0.10-0.30% | ~0.04-0.10% |
| Additional trading cost | None — bought/sold directly with the AMC | Bid-ask spread + brokerage + STT on every trade |
| Demat account required? | No | Yes |
| Best suited for | Automated monthly SIPs | Large lump-sum trades in liquid ETFs |
An ETF's lower headline expense ratio is real, but it's not the full cost of owning one. Every ETF purchase or sale happens on the stock exchange, which means you also pay the bid-ask spread (the gap between what buyers are willing to pay and sellers are willing to accept), brokerage, and Securities Transaction Tax on each trade — costs an index fund bought directly from the AMC simply doesn't have.
Liquidity varies enormously between ETFs
Heavily traded ETFs tracking the Nifty 50 or Nifty Next 50 — Nippon India Nifty BeES and SBI Nifty 50 ETF are commonly cited as the most liquid — typically have bid-ask spreads of just 0.05-0.15%. But liquidity drops off sharply beyond a handful of large, well-known ETFs: thinly traded sectoral or international ETFs can carry spreads of 0.50-2.00% per trade. A single round-trip in a thinly traded ETF can cost more than three years of the expense-ratio savings you were chasing in the first place.
Which one actually suits your investing style
For a monthly SIP — say ₹5,000 or ₹10,000 going in automatically every month — an index fund is almost always the smoother choice. SIPs into ETFs require either manual trading on each date or setting up recurring buy orders through your broker, and repeated small ETF trades multiply the spread and brokerage cost across dozens of transactions a year. For a large one-time lump-sum investment, a highly liquid ETF like a Nifty 50 tracker can work well, since a single trade's spread cost is proportionally small against a large amount, and the ETF's lower expense ratio compounds meaningfully over a long holding period.
The account-access difference
Index mutual funds can be bought directly through the AMC's website, app, or any mutual fund investing platform — no demat account required. ETFs, being exchange-traded, require a demat and trading account, adding a layer of account setup and, for many brokers, per-trade charges that a direct mutual fund purchase avoids entirely.
Key takeaways
- ETFs have a lower headline expense ratio, but every trade adds bid-ask spread, brokerage, and STT — costs an index fund bought from the AMC doesn't carry.
- Liquid, large ETFs (Nifty 50/Nifty Next 50 trackers) keep spreads tight (0.05-0.15%); thin sectoral/international ETFs can cost 0.50-2.00% per trade.
- Index funds fit automated monthly SIPs better — no demat account needed, no repeated trading friction.
- ETFs suit large, infrequent lump-sum trades in genuinely liquid names, where the lower expense ratio compounds meaningfully over time.
- A demat account is mandatory for ETFs; index mutual funds can be bought without one.
Frequently Asked Questions
Do index funds and ETFs tracking the same index give the same returns?
They aim to, but small differences (tracking error, expense ratio, and for ETFs, how close the trade price was to the actual NAV) mean returns won't be identical, even if very close over a long holding period.
Is a Direct index fund plan always cheaper than an ETF?
Not necessarily — an ETF's headline expense ratio is usually lower than even a Direct index fund's. The comparison flips once you factor in trading costs, which matters far more for frequent small purchases (SIPs) than for a single large trade.
Can I do a SIP into an ETF?
Yes, most brokers support recurring buy orders for ETFs, but each purchase still incurs the bid-ask spread and brokerage — over many small monthly purchases, this friction typically outweighs the ETF's lower expense-ratio advantage compared to an index fund SIP.
Which is better for a complete beginner with no demat account?
An index fund is the simpler starting point — no demat account setup, no need to understand bid-ask spreads or place market orders, just a straightforward SIP or lump-sum purchase through an AMC or mutual fund platform.
Do international or sectoral ETFs follow the same cost logic?
The same principle applies but the numbers are worse — international and sectoral ETFs are typically far less liquid than broad-market index ETFs, meaning wider spreads and higher effective trading costs, so the case for a mutual fund equivalent (where one exists) is usually stronger.