Forex Position Size Calculator (AUD)

How to use this calculator

Enter your account balance and currency, the percentage of the account you are prepared to lose if the stop is hit, the stop-loss distance in pips, and the pair. The calculator returns the position size in standard lots and units, the pip value at that size, and the exact dollars at risk. Sizes round down to the 0.01-lot step brokers actually accept, so the risk figure never exceeds your limit.

The stop distance is the input traders most often guess. Measure it from your entry to the invalidation level your analysis gives you, then let the position size absorb the difference. A wider stop with a smaller position risks the same dollars as a tight stop with a larger one.

The position sizing formula

Lots = (balance x risk % / 100) / (stop-loss pips x pip value of 1.00 lot). The pip value term converts the pair's quote currency into your account currency, which is why the same trade sizes differently in AUD and USD accounts. Our pip value calculator shows that conversion on its own.

Every part of the formula is observable before the trade: balance from your account, risk percentage from your plan, stop distance from your analysis, pip value from current exchange rates. Nothing in it predicts the market; it only fixes the cost of being wrong.

Why risk percentage beats fixed lots

Trading a fixed lot size means your risk per trade drifts as your balance changes and as you switch pairs with different pip values. A percentage rule scales both ways: losses shrink the next position, wins grow it, and the account compounds without any single trade being able to do outsized damage. Ten consecutive 1% losses leave about 90% of the account intact; ten fixed-size losses on an oversized lot can halve it.

The percentage rule is also what makes performance comparable across pairs. A 25-pip stop on AUD/USD and a 40-pip stop on GBP/JPY carry the same dollar risk once the position is sized to the stop, so your win rate and average return stop depending on which pair you happened to trade. New traders can start with the framework in our beginner forex broker guide.

Stop-loss distance and volatility

Stops placed inside a pair's normal hourly range get hit by noise rather than by being wrong. Volatile pairs and news sessions need wider stops, which the formula automatically compensates for with a smaller position. The common failure is the reverse: keeping the position size fixed and tightening the stop to force the maths, which converts one planned loss into several unplanned ones.

Position sizing also interacts with leverage limits. The size this calculator returns still has to fit within your margin, which ASIC caps at 30:1 on major pairs for retail accounts; the leverage guide explains the caps and our margin calculator shows the margin a given size requires. If the required margin exceeds your free equity, the constraint that binds is margin, not risk, and the position must shrink to fit both.