Position Size

 
double LotSize(int SL, double mRisk,double MaxLot)
  {

   double lotSize;
   SL=SL*10;


   double lotstep=MarketInfo(_Symbol,MODE_LOTSTEP);
   double lotdigit=MarketInfo(_Symbol,MODE_DIGITS);
   double tickvalue=MarketInfo(_Symbol,MODE_TICKVALUE);

   double risk = mRisk * AccountBalance()/100;

   double lotsize  =risk/(SL*tickvalue);


   lotSize=MathRound(tradesizecheck(lotsize,MaxLot)/lotstep)*lotstep;

   if(lotstep>=0.1)
      lotSize=NormalizeDouble(lotSize,1);
   else(lotSize=NormalizeDouble(lotSize,2));



   return(lotSize);
  }
Hello! I Believe it has been discussed this subject. Kindly point me to the threads. I have made a sort off calculation for the sizes, but it will only work for FX. I have tried today for US100 for example but I am missing something … instead of 0.19 I get 0.019 . Thank you! 
 

Risk depends on your initial stop loss, lot size, and the value of the symbol. It does not depend on margin and leverage. No SL means you have infinite risk (on leveraged symbols). Never risk more than a small percentage of your trading funds, certainly less than 2% per trade, 6% total.

  1. You place the stop where it needs to be — where the reason for the trade is no longer valid. E.g. trading a support bounce, the stop goes below the support.

  2. AccountBalance * percent/100 = RISK = OrderLots * (|OrderOpenPrice - OrderStopLoss| * DeltaPerLot + CommissionPerLot) (Note OOP-OSL includes the spread, and DeltaPerLot is usually around $10/PIP, but it takes account of the exchange rates of the pair vs. your account currency.)

  3. Do NOT use TickValue by itself - DeltaPerLot and verify that MODE_TICKVALUE is returning a value in your deposit currency, as promised by the documentation, or whether it is returning a value in the instrument's base currency.
              MODE_TICKVALUE is not reliable on non-fx instruments with many brokers - MQL4 programming forum (2017)
              Is there an universal solution for Tick value? - Currency Pairs - General - MQL5 programming forum (2018)
              Lot value calculation off by a factor of 100 - MQL5 programming forum (2019)

  4. You must normalize lots properly and check against min and max.

  5. You must also check Free Margin to avoid stop out

  6. For MT5, see 'Money Fixed Risk' - MQL5 Code Base (2017)

Most pairs are worth about $10 per PIP. A $5 risk with a (very small) 5 PIP SL is $5/$10/5 or 0.1 Lots maximum.