Position Sizing
Deciding how much money to put in each investment based on risk.
Why it matters
Most beginners pour all their energy into picking the right stock. The investors who last do something quieter first: they decide how much to put into each position. Position sizing, not stock picking, is what keeps a single bad trade from wiping you out. You can be wrong many times and still come out ahead, as long as no one loss is large enough to end the game. Survival comes first, returns come second.
A great company can still fall hard for reasons no one could have seen. If too much of your money sits in that one name, an ordinary drop becomes a permanent dent. Size every position so that being wrong costs you a little, never everything.
An everyday way to picture it
A disciplined poker player never pushes the whole stack in on one hand, however strong it looks. They bet a small slice of their chips, because even a great hand loses often enough that a single all-in can end the night. The point of staying small is simple: be there for the next hand.
Position sizing is that same discipline for investing. You decide in advance how thin a slice of your capital one position is allowed to cost you, so no single trade can knock you out of the game. It is the old rule about never putting all your eggs in one basket, turned into a number.
How the sizing actually works
The core rule is simple and almost never broken by professionals: never risk more than a small fixed share of your total capital on any one position, commonly 1 to 2 percent. Risk here means the rupees you would lose if the trade went against you and you sold at your stop, not the total amount you put in.
How many shares that buys depends on one thing beginners tend to ignore: the distance to your stop. A tight stop sits close to your entry, so each share risks little and you can hold more of them. A wide stop risks more per share, so you must hold fewer. Position size is set by the stop, not by how strongly you believe in the idea.
The same ₹20,000 of risk on a ₹500 stock buys very different amounts depending only on where the stop sits. The rupees at risk stay fixed, the share count moves.
| Stop (entry ₹500) | Risk per share | Position size | Money in the trade | Max loss |
|---|---|---|---|---|
| ₹480, 4 percent away | ₹20 | 1,000 shares | ₹5,00,000 | ₹20,000 |
| ₹450, 10 percent away | ₹50 | 400 shares | ₹2,00,000 | ₹20,000 |
| ₹400, 20 percent away | ₹100 | 200 shares | ₹1,00,000 | ₹20,000 |
This is also why concentration is dangerous. Putting half your capital into one conviction bet feels bold, but it hands a single company the power to sink your whole account. Spreading capital across several positions means one blow-up costs you a slice, not the whole pie. The arithmetic of ruin is unforgiving: bet too big and a normal losing streak, which every investor hits, can leave you with too little to recover from.
| Risk per trade | Capital left after 5 losses in a row | What it means |
|---|---|---|
| 2 percent | ₹9,03,921 | Barely a scratch. You stay in the game. |
| 10 percent | ₹5,90,490 | A real dent, but recoverable. |
| 25 percent | ₹2,37,305 | Most of your capital is gone. |
| 50 percent | ₹31,250 | All but wiped out. |
| 100 percent | ₹0 | One loss ends the game. |
- Sizing by conviction. The surer you feel, the bigger you bet. Conviction does not lower the odds of being wrong, it only raises the cost of it.
- Forgetting the stop. Without a stop you have no idea what a single share actually risks, so there is nothing to size against.
- Doubling down on losers. Adding to a falling position to average down quietly turns a planned small loss into a large one.
See it for yourself
Set your capital, the risk you will accept, the entry, and the stop. The calculator turns those into the exact number of shares to buy.
Worked example: a ₹10,00,000 account
Suppose you have ₹10,00,000 to invest and a stock you like trades at ₹500. You decide, before anything else, that this one position may cost you no more than 2 percent of your capital. Here is how that single rule turns into a precise number of shares.
| Step | Working | Result |
|---|---|---|
| Total capital | What you have to invest | ₹10,00,000 |
| Risk per trade | The most you will lose on this position | 2 percent |
| Risk amount | ₹10,00,000 × 2 percent | ₹20,000 |
| Entry price | What you pay per share | ₹500 |
| Stop price | 10 percent below entry | ₹450 |
| Risk per share | ₹500 - ₹450 | ₹50 |
| Position size | ₹20,000 ÷ ₹50 | 400 shares |
| Money in the trade | 400 × ₹500 | ₹2,00,000 |
If the stop at ₹450 is hit, you sell your 400 shares for a loss of ₹20,000, exactly the 2 percent you set aside to risk. The trade can go wrong and your account barely notices. Notice too that you put ₹2,00,000, a fifth of your capital, into a single name, which is already plenty of concentration for one idea.
Your call: size it, or back your conviction
You are very confident in this ₹500 stock. The rule says 400 shares for ₹2,00,000. The temptation is to go much bigger. Which do you do?
Remember this
| Rule | Why it keeps you alive |
|---|---|
| Risk 1 to 2 percent per trade | No single loss can wipe you out. |
| Let the stop set the size | A wider stop means fewer shares for the same rupee risk. |
| Never oversize on conviction | Feeling sure does not change the odds of being wrong. |
| Spread across positions | One blow-up dents the portfolio, it does not end it. |
| Cut, do not double down | Adding to a loser turns a small loss into a large one. |
In short: position sizing, not stock picking, is what keeps you in the game. Decide how much you can afford to lose before you decide how much to buy, and let the stop tell you the rest.