Position Size Calculator

How to Use the Position Size Calculator

1. Account size. Enter the cash value of the trading account, not money you might add later.
2. Risk per trade. Enter the percentage of the account you accept to lose if the stop loss is hit. Many disciplined swing traders keep this between 0.5% and 1%.
3. Entry and stop loss. Enter where you plan to buy and where the trade idea is proven wrong, usually just below support or the last higher low.
4. Target (optional). Add a realistic target to see the reward-to-risk ratio before you commit.

The share count updates as you type. If the posi­tion would cost more than the account holds, the cal­cu­la­tor caps the size at what you can actu­ally afford and tells you so.

The Position Size Formula Behind the Numbers

The first part gives the money at risk: a $10,000 account risking 0.5% puts $50 on the line. The second part gives the risk per share: an entry at $50 with a stop at $48 risks $2 on every share. Divide $50 by $2 and the answer is 25 shares, a $1,250 posi­tion. This is the same worked example used in our full guide to Risk rules, which also covers stop place­ment and port­fo­lio expo­sure in depth.

Notice what decides the size: the dis­tance to the stop, not how con­fi­dent you feel. A wider stop means fewer shares; a tighter stop allows more. Either way, the money lost at the stop stays the same, which is the whole point of posi­tion sizing.

Choosing Your Risk per Trade and Stop Loss

A stop loss should sit where the chart says the idea is wrong, such as below a support zone, a break­out level or a rising moving average, never at a round number picked to make the size look bigger. Price Structure helps you find that level; the cal­cu­la­tor then turns it into a share count.

Risk per trade is a per­sonal rule, and a small one sur­vives losing streaks. At 1% risk, ten losses in a row cost about 10% of the account. At 5% risk, the same streak costs about 40%, and the maths of recov­er­ing from that is brutal. Pick a figure you could keep for a hundred trades, then let the cal­cu­la­tor apply it the same way every time.

What a Position Size Calculator Cannot Do

• It cannot stop price gaps: a stock can open below your stop after news, so the real loss can be larger than planned.
• It leaves out commissions, spreads and slippage, so keep a small buffer.
• It does not judge whether a setup is worth taking. That is the job of your research and trading plan.
• It is built for long positions in stocks; leveraged products such as CFDs need extra care with margin.

Use the result as a ceiling, not a target. If the chart, the market or your own state of mind is unclear, a smaller size or no trade at all is a valid deci­sion.