Position Size Calculator
Work out exactly how many shares to buy for any trade based on the risk you are willing to take. Enter your account size, the percentage you want to risk, your entry price, and your stop-loss, and the calculator shows your position size and how much is at stake.
Shares to buy
20
Amount at risk
$100.00
Position value
$2,000.00
% of account
20.0%
For education only. This is not investment advice. All trading involves risk, and past performance is not indicative of future results.
How position sizing works
Position sizing keeps any single trade from doing outsized damage to your account. The math is simple: decide how much you are willing to lose on the trade (your risk amount), then size the position so that, if your stop-loss is hit, you lose only that amount.
- Risk amount = account size x risk per trade. Example: a $10,000 account risking 1% = $100.
- Risk per share = the distance between your entry and your stop-loss. Example: entry $100, stop $95 = $5 per share.
- Shares to buy = risk amount divided by risk per share. Example: $100 / $5 = 20 shares.
That way the same risk amount applies whether your stop is tight or wide, the position size adjusts to keep your downside consistent.
Position sizing and copy trading
Position sizing matters even more when you copy trade, because copying a larger account at full scale can put too much at risk on one trade. With RelayTrades, copied trades are scaled to your account with a sizing multiplier or maximum position size, and your limits (exposure, daily-loss caps, slippage protection) are enforced server-side before any order is placed. Pair this with the risk/reward calculator to check whether a trade is worth taking, and learn more about managing copy trading risk.