TL;DR: Under the 1% rule, number of lots = (capital × 1%) ÷ (stop distance × lot size). With Nifty at 65 units per lot and Bank Nifty at 30, a ₹5 lakh account risking ₹5,000 can trade 3 Nifty option lots with a ₹20 premium stop. If one lot's risk exceeds 1%, the right size is zero, not one.
Most blown-up F&O accounts didn't die from a bad strategy. They died from one good-looking trade sized at five lots when the account could carry one.
Lot sizing in India has a quirk that global position-sizing guides miss: you can't buy 2.4 lots. Exchange lot sizes force your risk into fixed steps, and on a small account, the smallest step is often bigger than 1%. This guide works through the math with real Nifty and Bank Nifty numbers.
The Root Problem: Traders Size by Conviction, Not by Stop Distance
Most retail traders pick their lot count first and their stop-loss second, which makes risk per trade random. The same "2 lots" can risk ₹1,300 on one trade and ₹9,000 on the next, depending on where the stop happens to be.
The fix is to reverse the order:
- Find your entry.
- Find your stop-loss. This defines your risk per unit, not your position size.
- Decide your rupee risk for the trade (at most 1% of capital).
- Back into the lot count from those numbers.
Conviction can change how likely you think the trade is to work. It should never change how much of your account is on the line.
Why 1%? Because losing streaks are normal, and recovery is asymmetric.
| Risk per trade | Account after 10 straight losses | Gain needed to recover |
|---|---|---|
| 1% | −9.6% | +10.6% |
| 2% | −18.3% | +22.4% |
| 5% | −40.1% | +67.0% |
Ten losses in a row sounds rare. For a strategy with a 40% win rate, any given run of ten trades has about a 1-in-165 chance of being all losses. At 6–7 trades a day, that's roughly a year of trading, so expect to see it. At 5% risk, that streak leaves you needing a 67% return just to get back to where you started.
The Breakdown: Position Size Formulas for Nifty and Bank Nifty
Number of lots = rupee risk ÷ (stop distance per unit × lot size), always rounded down. Everything else is plugging in numbers.
The inputs
- Capital: the money in your trading account, not your net worth.
- Risk %: 0.5–1% for most active traders; 2% is an upper limit.
- Stop distance: entry price minus stop price, in premium points for options or index points for futures.
- Lot size: NSE currently sets Nifty at 65 and Bank Nifty at 30 units per lot, effective from the January 2026 series. NSE revises lot sizes periodically, so check the current contract specification before you size a trade.
Example 1: Nifty option buyer, ₹5 lakh account
- Capital: ₹5,00,000 at 1% risk = ₹5,000
- Buy a Nifty call at ₹140, stop at ₹120 → stop distance ₹20
- Risk per lot: ₹20 × 65 = ₹1,300
- Lots: ₹5,000 ÷ ₹1,300 = 3.85 → 3 lots (₹3,900 at risk)
Example 2: Bank Nifty option buyer, same account
- Risk budget: ₹5,000
- Buy a Bank Nifty put at ₹310, stop at ₹250 → stop distance ₹60
- Risk per lot: ₹60 × 30 = ₹1,800
- Lots: ₹5,000 ÷ ₹1,800 = 2.78 → 2 lots (₹3,600 at risk)
Example 3: Nifty futures, same account
- Risk budget: ₹5,000
- Long at 25,000, stop at 24,940 → stop distance 60 points
- Risk per lot: 60 × 65 = ₹3,900
- Lots: ₹5,000 ÷ ₹3,900 = 1.28 → 1 lot
Futures risk adds up fast. A 100-point stop on one Nifty futures lot is ₹6,500, already over 1% of a ₹5 lakh account.
Add charges to your risk
Your real loss on a stopped-out trade is the stop distance plus charges, so include roughly ₹80–100 per option round trip in your risk budget. For a Nifty option trade of 2 lots, Zerodha-style charges (₹40 brokerage, 0.15% STT on the sell, exchange fees, stamp duty and GST) come to about ₹85. On futures, the April 2026 STT increase to 0.05% pushed a one-lot Nifty round trip to roughly ₹950.
On small risk budgets this matters. If you risk ₹1,000 per trade, ₹90 of charges is 9% of it.
The Lot-Size Trap: When One Lot Is Already Too Big
If the risk on a single lot exceeds your 1% budget, the correct position size is zero. Taking one lot "because you can't trade less" is how small accounts end up risking 3–5% per trade without noticing.
Maximum stop distance you can afford for one lot at 1% risk:
| Account size | 1% risk | Max stop, 1 Nifty lot (65) | Max stop, 1 Bank Nifty lot (30) |
|---|---|---|---|
| ₹1,00,000 | ₹1,000 | ₹15.4 per unit | ₹33.3 per unit |
| ₹3,00,000 | ₹3,000 | ₹46.2 per unit | ₹100.0 per unit |
| ₹5,00,000 | ₹5,000 | ₹76.9 per unit | ₹166.7 per unit |
| ₹10,00,000 | ₹10,000 | ₹153.8 per unit | ₹333.3 per unit |
On a ₹1 lakh account, a Nifty option trade whose chart stop is ₹25 away risks ₹1,625, which is 1.6%. Your choices are:
- Skip the trade. Not every setup fits your account.
- Choose a different strike where a ₹15 stop is structurally valid. Moving the stop closer just to fit the math only guarantees more stop-outs.
- Accept a higher risk % knowingly, and cap the number of such trades.
What you should not do is trade one lot and pretend it's 1%.
Stops are not guarantees
Option premiums can gap through your stop, especially around big moves or close to expiry. Size assuming some slippage, and treat the formula's output as a ceiling.
Position Size Tells You What You Can Lose; Risk-Reward Tells You If It's Worth It
A well-sized trade with poor risk-reward is still a losing habit, just a slower one. Your reward-to-risk ratio sets the win rate you need just to break even:
| Reward : risk | Breakeven win rate |
|---|---|
| 1 : 1 | 50.0% |
| 1 : 2 | 33.3% |
| 1 : 3 | 25.0% |
Most discretionary traders don't know their actual average reward-to-risk. If you're taking 1:1 setups, you need to win half your trades just to tread water, and that's before charges.
WickLog's free risk-reward calculator showing a 1:3 setup with a 25% breakeven win rate
How to Check Whether You Actually Size This Way
Compare your planned risk with your actual average loss; if the average loss is bigger, your sizing or your stop discipline is leaking. This is where a journal earns its keep.
- Use the free calculators. WickLog's position size calculator gives shares or lots from capital, risk % and stop distance. The risk-reward calculator shows your breakeven win rate: at 1:2 reward to risk, you need just over 33%.
- Log the stop with every trade. WickLog's trade form has stop-loss and target fields. With Zerodha sync on Pro, pending stop-loss and GTT trigger prices are imported as the trade's stop.
- Watch average loss vs average win. The Key metrics widget shows both, free. If your average loss is 1.8× your average win, your stops are moving.
- Ask the question directly. On Pro, Ticker AI, WickLog's conversational trading assistant, can answer "How often did my loss exceed my logged stop distance last month, and by how much?"
Key Takeaways
- Lots = rupee risk ÷ (stop distance × lot size), rounded down. Pick risk first, lots last.
- At Nifty 65 and Bank Nifty 30 per lot, a ₹1 lakh account can only afford a ₹15 Nifty option stop on one lot at 1% risk.
- If one lot breaks your 1% budget, the answer is zero lots, a different strike, or a deliberate exception, never a quiet 3% bet.
- Budget charges into risk. About ₹85 per option round trip and roughly ₹950 per Nifty futures round trip after the April 2026 STT hike.
- Verify with data. Average loss larger than planned risk means your stops or your sizing are slipping.
Frequently Asked Questions
How many lots of Nifty should I trade with ₹1 lakh capital?
At 1% risk, ₹1 lakh gives a ₹1,000 risk budget, so one Nifty lot of 65 only fits if your stop is within about ₹15 per unit. For most option setups that means trading one lot at most, and skipping trades with wider stops. For Nifty futures, one lot needs a stop under about 15 points, which is rarely realistic.
What is the 1% rule in trading?
The 1% rule means never risking more than 1% of your trading capital on a single trade, measured from entry to stop-loss. It keeps a normal losing streak, such as 10 losses in a row, to a drawdown of under 10%.
Is WickLog's position size calculator free?
Yes. WickLog's position size, risk-reward and trading expectancy calculators are free public tools that need no account. Logging trades and checking your actual risk against plan works on the free journal plan.
Audit Your Sizing Against Your Real Trades
The calculator tells you what you should risk. Your tradebook tells you what you actually risked. Import last month's trades and compare your average loss with your 1% budget.