Entries get the blame; size does the damage
Ask a trader why the account is down 40% and you'll hear about entries — the breakout that failed, the support that didn't hold. Look at the actual trade log and the story is almost always different: forty small trades that roughly broke even, and three enormous ones that did all the damage. The entries were ordinary. The size was not.
The arithmetic is unforgiving. A trader risking ₹4,000 a trade can be wrong five times in a row and lose ₹20,000 — annoying, survivable, reviewable. The same trader risking ₹60,000 on one “sure thing” needs to be wrong exactly once. Sizing is the only trading decision where a single error can end the whole project, which is why it deserves more measurement than it usually gets.
Lots make sizing lumpy
Equity traders can size in single shares. F&O traders cannot: NIFTY moves in lots of 75, SENSEX in lots of 20, stock futures in whatever the exchange says. You cannot risk 1.3 lots. Sizing moves in steps, and on a small account the smallest step may already be too big.
Run the numbers on a ₹2,00,000 account with a 1% risk budget — ₹2,000 per trade. A NIFTY weekly option quoting ₹150 costs ₹11,250 for one lot. If your stop is the full premium, that single lot is 5.6% of the account — nearly six times the budget. No entry timing fixes that; the position is oversized before the first tick. The uncomfortable but honest conclusion is that account size dictates which instruments you can size responsibly, and the journal's job is to show you when you've been pretending otherwise.
The 1–2% rule, translated into rupees
The classic rule — risk 1–2% of capital per trade — only becomes useful once you write it in rupees. On a ₹5,00,000 account, that's ₹5,000 to ₹10,000 of maximum loss per trade. What that number means depends entirely on the structure of the position:
- Option buying: worst-case risk is premium × lot size × lots. One lot of a ₹150 NIFTY option is ₹11,250 at risk if you'd let it go to zero — already outside a 1% budget. With a stop at half the premium, the same lot risks about ₹5,600 and just fits. Two lots don't.
- Spreads: defined-risk structures make the budget easy to respect. A debit spread with a net cost of ₹70 risks ₹5,250 per lot, and that number cannot grow overnight. This is why smaller accounts often find spreads easier to size honestly — the maximum loss is printed on the trade at entry.
- Naked selling: the trap is reading the margin as the risk. Selling an index option might block ₹85,000 of margin and collect ₹4,000 of premium — but a gap open can hand you a ₹40,000 loss on that same position. The risk lives in the tail, not the margin statement, and it deserves far more respect than one line of a risk budget.
None of this says which structure to trade. It says that whatever you trade, the rupee risk per trade is computable in advance — and a journal should record it, because after the fact is when the number gets rewritten in your memory.
“One more lot” and its evil twin
Sizing discipline rarely dies in a crash. It dies in two quiet, predictable moments. The first comes after a winning streak: three green days at 2 lots, and the fourth day is suddenly traded at 4, because it “feels” earned. Nothing about your edge doubled overnight — only your exposure did. The streak that funded the confidence is exactly what the doubled size gives back.
The second comes after a loss: doubling down to “recover”, sizing the next trade to win back the last one. That is revenge trading expressed in lots, and it has a signature any journal can detect — position size correlating with the previous trade's P&L instead of with a plan. In a disciplined account, yesterday's result and today's size have nothing to do with each other.
Discipline is a flat size distribution
Here is the useful reframe: sizing discipline is not a feeling of being careful. It is a shape in your data — a flat distribution of position sizes, month after month. Three numbers from your own journal tell you whether you have it:
- Largest trade vs median trade. If your median position risked ₹5,000 and your largest risked ₹22,000, your rule wasn't a rule — it was a mood with exceptions. A ratio near 1 is what discipline actually looks like.
- The “oversized” tag, totalled in rupees. Tag every trade that exceeded your budget and sum the P&L. Most traders find the tag is deep in the red —pricing the mistake is what makes the habit expensive enough to quit.
- Where the losses cluster. Sort the month's trades by size and look at the biggest five. If your worst losses live there — and they usually do, because the big positions are the emotional ones — the data has named your problem for you.
Checking these by hand from a broker statement is tedious, which is why almost nobody does it. PnL Book builds the trade log for you — screenshot import, FIFO round-trips, mistake tags with rupee totals — so the size distribution is just there to look at every week, next to the question that matters: were my biggest trades my best decisions, or my worst?
You don't need a better entry signal. You need every position to be the size you decided on in advance — and a record honest enough to show you when it wasn't.