Disclosure: written by the developer of Prop Firm Risk Manager PRO EA.

How to calculate position size on a prop firm account in MT5

Correct position sizing keeps one bad trade from consuming your daily drawdown. The formula is short; the discipline is in applying it every time.

The basic formula

Lot size = (Account value × Risk %) ÷ (Stop distance in pips × Pip value per lot)

Example: a USD 100,000 account risking 0.5% (USD 500) with a 25-pip stop on a pair where one pip is worth about USD 10 per standard lot gives 500 ÷ (25 × 10) = 2.0 lots. Pip value changes by symbol and account currency, so confirm it in MT5 for each instrument.

Choose a risk per trade that fits the drawdown limit

If your daily limit is 5%, risking 1% per trade means five straight losses can reach it. Many traders choose a smaller figure so that a bad run still leaves room. Pick yours deliberately and stay consistent.

Do not ignore open risk

Single-trade risk is only half the picture. Three trades at 0.5% each that all move against you together are 1.5% at risk. Add the risk of all open positions, treat trades without a stop-loss as unknown risk, and keep the total inside your headroom.

Correlation and stacking

Several positions on correlated pairs (for example multiple USD pairs in one direction) behave like one larger position. Size them as a group.

Automating the check

Prop Firm Risk Manager PRO EA can calculate lot size from your risk percentage and stop distance, validate orders it submits against your limits before execution, and show total open risk on the chart. It is a tool for discipline: you still choose the trades.

Educational content, not financial advice or a trading signal. Always confirm rules with your prop firm. No tool guarantees profitability, challenge success or loss prevention.