nCalculate Lot by Percent - library for MetaTrader 5

Module of lot calculation by risk percentage

Purpose:

Automatically calculates the size of a trading position (lot) so that the potential loss when a stop loss is triggered is a specified percentage of your deposit. This is the basis of competent money management.

How it works:

1. You set:risk percentage (for example, 2%) and stop loss price.

2. The function calculateshow much you can trade for to lose no more than 2% of your account if the price reaches the stop.

3. The function translates this amount into lots, taking into account the specification of the instrument at your broker.

Key features:

• Smart logic: automatically applies the correct formula for pairs like EURUSD and USDJPY .

• Checks: monitors correct prices, minimum and maximum lots.

• Ready to use: one function call returns the lot to be sent to the market order.

Example of use in the code:

// Risk 1.5% of the deposit by placing a stop loss at 1.08500
double myLot = Calculate_Lot_by_Percent(1.5, 1.08500);

if(myLot > 0) {
    // Open a deal with the calculated lot
    trade.Sell(myLot, _Symbol, 0, 1.08500, 0, "Trade with 1.5% risk");
}

Bottom line: this code gets rid of manual calculations and helps you maintain risk discipline in every trade. Simply plug it into your EA or script.