Building Your First MQL5 Expert Advisor

MetaTrader 5 (MT5) comes with a powerful built-in programming language called MQL5. With it, you can automate any strategy.

Prerequisites

• MT5 installed (free from your broker)
• Basic programming concepts (variables, loops, conditions)
• A strategy you want to automate

Your First EA: A Simple Moving Average Crossover

//+------------------------------------------------------------------+
//| SimpleMAExpert.mq5                                              |
//+------------------------------------------------------------------+
input int FastMA = 10;      // Fast MA period
input int SlowMA = 30;      // Slow MA period
input double LotSize = 0.01; // Position size

int fastHandle, slowHandle;

int OnInit() {
   fastHandle = iMA(_Symbol, _Period, FastMA, 0, MODE_SMA, PRICE_CLOSE);
   slowHandle = iMA(_Symbol, _Period, SlowMA, 0, MODE_SMA, PRICE_CLOSE);
   return INIT_SUCCEEDED;
}

void OnTick() {
   double fast[], slow[];
   CopyBuffer(fastHandle, 0, 0, 3, fast);
   CopyBuffer(slowHandle, 0, 0, 3, slow);
   
   if (fast[1] > slow[1] && fast[2] <= slow[2])
      Trade.Buy(LotSize);
   else if (fast[1] < slow[1] && fast[2] >= slow[2])
      Trade.Sell(LotSize);
}
//+------------------------------------------------------------------+

Testing Your EA

1. Open MT5 Strategy Tester
2. Select your EA, symbol, and date range
3. Choose tick-by-tick simulation for accuracy
4. Run the test and analyze the results (profit factor, drawdown, trades)

Deployment

Once tested:

1. Add the EA to a chart (drag from Navigator)
2. Enable algorithmic trading (Alt+T)
3. Monitor it for the first few days

Pro Tips

• Always use stop loss and take profit in your code
• Start with a demo account
• Don't automate more than 1% risk per trade
• Keep a manual journal alongside to track EA performance