Risk percentage lot size calculation

Hi All,

I would like to add to an existing and working MQL5 EA the ability to calculate the lot size based on a risk percentage. Or in other words how many percent of the account I'm willing to lose for each deal.

Here are some key elements of my EA setup:

The base currency is EUR

Trading pair is EURJPY

Leverage is 1/100

SL is fixed at 50 pips

Target risk percentage per deal should be a variable set by default on 5%  

The below formula seem to be the one needed to achieve my lot size calculation but I'm not sure. 

Lot Size = Amount Risked / Number of Pips x Pip Value 

I tried the created the code myself and here is where I stopped: 

Basically I need help to compete the "//Calculating Lot Size based on SL and Risk Percentage" part of the code. 

Let me know if you have any questions.  

Different Variables for the lot size calculation: 

input int      StopLoss=50;               // Stop Loss
input double   RiskPercentage=5;          // Lots to Trade

int STP, TKP; 
double LotSize;
double Pips;



//--- Let us handle currency pairs with 5 or 3 digit prices instead of 4
   STP = StopLoss;
   TKP = TakeProfit;
   if(_Digits==5 || _Digits==3)
     {
      STP = STP*10;
      TKP = TKP*10;
     }
   return(0);
  }

 My Buying Script

if(Buy_Condition_1 && Buy_Condition_2)
     {
         // any opened position?
         if((Buy_opened)||(Sell_opened))
           {
            //Alert("We already have an open Position. Oportuinity passed.");
            return;    // Don't open a new Buy Position
           }
           
         // Calculating Lot size based on SL and Risk Percentage
         
         MqlTick latest_price;
         SymbolInfoTick(_Symbol,latest_price);
         
         Pips = (latest_price.bid - STP)/_Point;          
         
         double AccountBalance = AccountInfoDouble(ACCOUNT_BALANCE);
         double TickValue = SymbolInfoDouble(_Symbol,SYMBOL_TRADE_TICK_VALUE);
         LotSize = (AccountBalance * (RiskPercentage/100))/(Pips * TickValue);  
         
         Print("Pips ", Pips, " Acc Bal: ", AccountBalance," Tick Val ", TickValue," Lot Size ", LotSize);      
         
         //Executing the Trade 
         ZeroMemory(mrequest);
         mrequest.action = TRADE_ACTION_DEAL;                                    // immediate order execution
         mrequest.price = NormalizeDouble(latest_price.ask,_Digits);             // latest ask price
         mrequest.sl = NormalizeDouble(latest_price.ask - STP*_Point,_Digits);   // Stop Loss
         mrequest.tp = NormalizeDouble(latest_price.ask + TKP*_Point,_Digits);   // Take Profit
         mrequest.symbol = _Symbol;                                              // currency pair
         mrequest.volume = LotSize;                                                  // number of lots to trade
         mrequest.magic = EA_Magic;                                              // Order Magic Number
         mrequest.type = ORDER_TYPE_BUY;                                         // Buy Order
         mrequest.type_filling = ORDER_FILLING_FOK;                              // Order execution type
         mrequest.deviation=100;                                                 // Deviation from current price
         //--- send order
         OrderSend(mrequest,mresult);
         // get the result code
         if(mresult.retcode==10009 || mresult.retcode==10008) //Request is completed or order placed
           {
            Alert("A Buy order has been successfully placed with Ticket#:",mresult.order,"!!");
            SendNotification("BBWP added a new Buy order!");
           }
         else
           {
            Alert("The Buy order request could not be completed -error:",GetLastError());
            ResetLastError();           
            return;
           }
        
     }