How the NIFTY is calculated
Understand that an index is a weighted average, so you know why the NIFTY can rise on a day when most of its constituents fell.
Runs entirely in your browser — nothing you type is sent anywhere. Educational only, and not investment advice.
How to use this calculator
Each step names a control you will find on screen above.
- Look at the weights before touching anything
Note how uneven they are. The top few names carry a share of the index wildly out of proportion to their count.
- Use free-float market cap
Toggle this on — it is what NSE actually does. Only shares available to trade are counted, so promoter and government holdings are excluded.
- Watch a heavyweight’s weight change
A company with a 50% promoter holding sees its index weight halve under free-float. This is why some enormous companies matter less to the index than their size suggests.
- Move one large constituent
Change the biggest name by a few percent and watch the index level. Then do the same to the smallest and compare.
Worked example: Why the index rose on a red day
Compare a full market-cap weighting against the free-float weighting the exchange actually uses, then move the largest constituent.
What to enter
- Use free-float market cap
- On
- Move the largest constituent
- +3%
What it shows you
- Top 5 constituents
- ≈ 40% of the index
- Bottom 25 combined
- a much smaller share
- Largest name +3%
- lifts the index noticeably on its own
- A high-promoter-holding company
- weight roughly halves under free float
Where this is taught
A calculator gives you a number. These explain what the number means and when it misleads you.
- Market Basics9 minIndices, largecaps, midcaps and smallcapsWhat the NIFTY actually measures, why it can rise on a day most stocks fell, and how SEBI defines the size buckets.
- Market Basics11 minHow an index is actually builtFree float, weighting, rebalancing and the rules behind the number quoted every evening. Knowing them explains what your index fund really owns.
- Technical Analysis13 minThe index chart nobody can tradeAn index has no order book, no bid, no volume and no trade. It is a number recomputed continuously from other people’s prices, and several things a chart reader assumes about it are properties of the formula rather than of the market.
- Market Basics13 minWhat each Indian sector actually doesA plain guide to the major sectors: how each makes money, what drives it, and the one number that matters most in each.
- Technical Analysis12 minWhen six positions are really one betPosition sizing protects you per trade. Correlation is what happens when every trade turns out to be the same trade on a bad day.