Position Sizing: How Many Shares Should You Buy?

Why size matters more than the entry

Two traders can take the exact same trade, with the same entry, stop-loss and target, and end up with very different results. The difference is how many shares each one bought. One risks a small slice of the account and can be wrong many times in a row without damage. The other puts so much into one idea that a single bad day changes everything.

Every strategy has losing streaks. Even a method that wins half the time will, sooner or later, lose five or six trades in a row just by chance. Position sizing is what lets you survive those streaks long enough for the method's average to show up. It is the part of trading you fully control, which is why it is worth learning before anything else.

The 1% risk rule

A widely used guideline is to risk no more than about 1% of your trading capital on one trade. Risk here does not mean the amount you invest. It means the amount you would lose if your stop-loss is hit.

With a capital of ₹5,00,000, 1% is ₹5,000. That is the most this one trade should cost you if it goes wrong. Some careful traders use 0.5%; a few aggressive ones use 2%. Going much higher means a normal losing streak can take a large share of the account.

The rule does not limit how big a position looks. A trade with a very close stop can use a large position and still risk only 1%. A trade with a wide stop must use a small one.

The formula, step by step

Step 1: decide the amount you are willing to risk (for example 1% of capital = ₹5,000).

Step 2: decide your entry and stop-loss from the chart. Say entry ₹800, stop-loss ₹776. The risk per share is ₹800 - ₹776 = ₹24.

Step 3: divide. Quantity = amount at risk ÷ risk per share = ₹5,000 ÷ ₹24 ≈ 208 shares.

Step 4: check the cost. 208 shares x ₹800 = ₹1,66,400. If that is more cash than you want in one stock, reduce the quantity. The formula gives the maximum, not a target.

Notice the order: the stop comes from the chart first, the quantity comes last. Beginners often do the opposite, buying a round number of shares and then placing the stop wherever the loss feels bearable. That puts the stop in a meaningless place.

Examples for different trade types

Intraday stock trade: capital ₹2,00,000, risk 0.5% = ₹1,000. Entry ₹410, stop ₹406, risk per share ₹4. Quantity = 250 shares. Intraday positions use margin, so the cash blocked is lower than 250 x ₹410, but the loss if the stop hits is still about ₹1,000 plus charges.

Swing trade: capital ₹5,00,000, risk 1% = ₹5,000. Entry ₹1,250, stop at ₹1,190 below support, risk per share ₹60. Quantity ≈ 83 shares, costing about ₹1,03,750.

Options buying: you cannot buy fractions of a lot, so size by lots. If one lot of an option costs ₹6,000 in premium and you plan to exit if the premium halves, your risk per lot is about ₹3,000. With ₹5,000 to risk, one lot fits; two lots would be too much. Remember that option premiums can fall fast, so the actual loss can be larger than planned.

Futures: one lot can represent lakhs of rupees of exposure. Risk per lot = points to your stop x lot size. A 50-point stop on a contract with a lot size of 75 is ₹3,750 per lot. This is why futures need especially careful sizing.

Don't forget charges and gaps

Brokerage, STT, exchange fees, GST and stamp duty add a little to every trade. For very small risk-per-share setups, such as a ₹1 stop on intraday, charges can be a big part of the loss. Include them when you calculate.

Gaps are the other hidden risk. If a stock opens 5% below your stop after quarterly results, the formula's "₹5,000 risk" can become ₹12,000. For overnight positions, especially around results, many traders deliberately use a smaller size.

Exposure limits: one more safety net

Besides risk per trade, set a limit on how much capital sits in one stock or one sector. Five trades that each risk 1% but are all bank stocks can all fall together on the same news. A simple rule such as "no more than 20% of capital in one stock and 30% in one sector" stops your trades from secretly being one big bet.

Also decide a daily loss limit. If you lose, say, 2% of capital in a day, stop trading for that day. Bad days are when the urge to "win it back" leads to oversized trades.

A worked example over ten trades

Imagine two learners, each with ₹3,00,000. Both take the same ten trades in a row: four winners that each reach a target twice the stop distance, and six losers that hit the stop. That is a realistic, slightly unlucky stretch.

Learner A risks 1% per trade, ₹3,000. The four winners add 4 x ₹6,000 = ₹24,000 and the six losers cost 6 x ₹3,000 = ₹18,000. After ten trades A is up about ₹6,000 before charges, and at no point was the account down more than about 6%.

Learner B ignores sizing and puts roughly ₹1,50,000 into each trade with a 6% stop, so each loss is about ₹9,000 and each win about ₹18,000. If the six losers come first, B is down ₹54,000, 18% of the account, before the first winner arrives. Many people stop following their plan, or start taking bigger trades to recover, long before the winners show up.

Same trades, same skill. The only difference is the size, and it decides whether the method gets a fair chance to work.

Practise it with virtual money

iTradeChart's free position size calculator does this math for you: enter capital, risk %, entry and stop-loss, and it shows the quantity and the money at risk. On the chart, the Long / Short drawing tool shows the same numbers for your plan before you place an order.

Practise with the ₹15 lakh paper account, using the auto-exit setting to close all positions if the day's total loss reaches your limit. The weekly Report card will flag trades where one position was too big compared to your account.