F&O Lot Sizes on NSE: What Changed and How It Affects Your Risk
One Nifty lot used to be 25 contracts. Today it's 75. That's a 3x increase in notional exposure per lot in under two years — and most traders are still sizing positions by "lots" rather than rupees at risk.
What actually changed
NSE has been revising lot sizes upward to keep contract values aligned with SEBI's minimum threshold (raised to ₹15 lakh in November 2024). Here's where the main indices stand:
- Nifty 50: 25 → 75 (notional ~₹18.4 lakh)
- Bank Nifty: 15 → 35 (notional ~₹17.9 lakh)
- FinNifty: 25 → 65
- Midcap Nifty: 50 → 120
- Sensex: 10 → 20
Why this matters more than it sounds
If you traded a Nifty ATM straddle a couple of years ago at ₹150 + ₹150 premium, one lot cost you ₹7,500 in premium with 25 qty. Same straddle today: 75 qty × ₹300 (premiums have also risen with vol) = ₹22,500 per lot. Triple the quantity, double the premium per leg — your max loss on a short straddle gone wrong scales accordingly.
Buying side looks "cheap" until you realize a 20-point adverse move on a 75-lot Nifty position is ₹1,500 gone. On Bank Nifty, a 50-point move against 35 qty is ₹1,750. These aren't small ticks anymore.
The margin angle
Short option margins have climbed proportionally. A Bank Nifty short strangle that needed ~₹1.2 lakh margin in 2022 now blocks closer to ₹1.7–1.9 lakh per lot depending on strikes. If you were sizing at "two lots" by habit, you're now deploying significantly more capital — and risking more in absolute terms — for the same label.
Charges scale too
STT on the sell side of options is 0.1% of premium. On a ₹300 premium × 75 qty sale, that's ₹22.50 per leg, vs ₹7.50 on the old lot. Brokerage is mostly flat per order, but exchange fees, SEBI charges, and GST all move with turnover. Run the actual numbers through the options profit calculator — the breakeven shift after charges is usually larger than people expect at these lot sizes.
What to actually do about it
Stop thinking in lots. Think in rupees at risk per trade and percentage of capital. A trader with ₹5 lakh capital taking "one lot" of a Bank Nifty short straddle is now sitting on ~₹17.9 lakh of underlying exposure — 3.5x leverage before you account for the unlimited-risk profile.
If your position sizing logic was built when Nifty lot was 50 or 25, it's stale. Rebuild it against current notional, not contract count.