Position Size Calculator
Work out exactly how much to trade so a single loss never costs more than you've decided it should.
Position sizing is the single most controllable variable in trading. You can't control whether a trade wins or loses, but you can control exactly how much of your account is on the line before you click buy or sell. This calculator turns that decision into a fixed, repeatable number instead of a guess.
The idea is simple: decide what percentage of your account you're willing to lose if the trade goes wrong, then size the position so that your stop loss — wherever you've placed it on the chart — corresponds exactly to that dollar amount. A trader risking 1% on a $10,000 account is willing to lose $100 on this trade, no more, regardless of how wide or tight the stop loss is.
This is different from picking a lot size out of habit. A 25-pip stop and a 100-pip stop require very different position sizes to represent the same dollar risk — the wider stop needs a smaller position, the tighter stop can support a larger one. Keeping risk constant across trades, rather than position size constant, is what separates consistent risk management from guesswork.
Use this tool before every trade, not just when something feels risky. Consistency is what makes the numbers mean anything over a long series of trades — a handful of oversized positions can undo the discipline of dozens of well-sized ones.