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How to calculate LOT size

  • Post #1
  • Quote
  • First Post: Jul 23, 2009 5:22am Jul 23, 2009 5:22am
Guys,

Is there any method to calculate the LOT size in MQL4?

Any formula available to calculate LOT size.

Please let me know

Cheers
Dipen
there was an EA somewhere here.. called Daily95pips... the following lotsize code is from that EA:

parameters:

Inserted Code
extern double FixedLots = 0.0;   // if > 0.0 fixed lots used
extern double Risk = 0.01;       // per cent of free margin of a single offer
extern int StopLoss = 30;
...
Inserted Code
double CalculateLotSize()
{
    if(FixedLots > 0.0)
        return (FixedLots);

    double pipValue = MarketInfo(Symbol(), MODE_TICKVALUE);
    double lots = AccountFreeMargin() * Risk / (StopLoss * pipValue);
    
    double lotStep = MarketInfo(Symbol(), MODE_LOTSTEP);
    int digits = 0;
    if(lotStep <= 0.01)
        digits = 2;
    else if(lotStep <= 0.1)
        digits = 1;
    lots = NormalizeDouble(lots, digits);
      
      double minLots = MarketInfo(Symbol(), MODE_MINLOT);
      if(lots < minLots)
          lots = minLots;
      
      double maxLots = MarketInfo(Symbol(), MODE_MAXLOT);
      if(lots > maxLots)
          lots = maxLots;
      
      return (lots);
}
forget about tomorrow, just steal away into the night
Hey spekitox.

Thanks for your code . it will helps.
Quoting spekitox
there was an EA somewhere here.. called Daily95pips... the following lotsize code is from that EA: parameters: extern double FixedLots = 0.0; // if > 0.0 fixed lots used extern double Risk = 0.01; // per cent of free margin of a single offer extern int StopLoss = 30; ... double CalculateLotSize() { if(FixedLots > 0.0) return (FixedLots); double pipValue = MarketInfo(Symbol(), MODE_TICKVALUE); double lots = AccountFreeMargin() * Risk / (StopLoss * pipValue); double lotStep = MarketInfo(Symbol(), MODE_LOTSTEP); int digits = 0; if(lotStep <= 0.01)...
It doesn't work.
using this code a 2000 account risking 200 dollars and using 150 pip stop range, on EURGBP pipvalue of 1.64 gives a .81 result which is 8 mini lots, when it should be .08.
What is better formula for Lot precision:
1)
double LOT=4.44999;
lots=MathMin(MathMax((MathRound(LOT/MarketInfo(Symbol(),MODE_LOTSTEP))*MarketInfo(Symbol(),MODE_LOTSTEP)),MarketInfo(Symbol(),MODE_MINLOT)),MarketInfo(Symbol(),MODE_MAXLOT));

or

double LOT=4.44999;
lots=MathMin(MathMax((int(LOT/MarketInfo(Symbol(),MODE_LOTSTEP))*MarketInfo(Symbol(),MODE_LOTSTEP)),MarketInfo(Symbol(),MODE_MINLOT)),MarketInfo(Symbol(),MODE_MAXLOT));


for first ans is 4.45 --- for second ans is 4.44
  • Post #6
  • Quote
  • Edited at 2:01pm Dec 25, 2019 1:47pm | Edited at 2:01pm
Quoting SalmanM
What is better formula for Lot precision: 1) double LOT=4.44999; lots=MathMin(MathMax((MathRound(LOT/MarketInfo(Symbol(),MODE_LOTSTEP))*MarketInfo(Symbol(),MODE_LOTSTEP)),MarketInfo(Symbol(),MODE_MINLOT)),MarketInfo(Symbol(),MODE_MAXLOT)); or double LOT=4.44999; lots=MathMin(MathMax((int(LOT/MarketInfo(Symbol(),MODE_LOTSTEP))*MarketInfo(Symbol(),MODE_LOTSTEP)),MarketInfo(Symbol(),MODE_MINLOT)),MarketInfo(Symbol(),MODE_MAXLOT)); for first ans is 4.45 --- for second ans is 4.44
Looking at the general approach the first one is "better" because more exact. "Better" in quotes because both may return invalid results. Both approaches miss a final NormalizeDouble(). Also it's recommended to move the min/max evaluation out of the formula and apply it in your strategy logic. Otherwise sooner or later you will experience surprises. A better general function looks like this:

Inserted Code
/**
 * Round a lot size according to the specified symbol's lot step value (MODE_LOTSTEP).
 *
 * @param  double lots              - lot size
 * @param  string symbol [optional] - symbol (default: the current symbol)
 *
 * @return double - rounded lot size
 */
double NormalizeLots(double lots, string symbol = "") {
   if (!StringLen(symbol))
      symbol = Symbol();
   double lotstep = MarketInfo(symbol, MODE_LOTSTEP);
   return(NormalizeDouble(MathRound(lots/lotstep) * lotstep, 2));
}

After you got the result you may apply min/max, or wrap min/max in a second helper function with a different name. Full source here: NormalizeLots()
after some years I find the best lot accuracy approach:
Inserted Code
double Lots=9.765433;
double LotStep=MarketInfo(Symbol,MODE_LOTSTEP);
if(LotStep==0) LotStep=1;
int FFF=-MathLog10(LotStep);
Lots=int(StringToDouble(DoubleToString(Pairs_Unified_Lots/LotStep,FFF)))*LotStep;

in this way, it is valid for lot step with tenth (1.2)or hundredth(1.23) or 0th (1) decimal
Here are 2 indicators that will calculate lot size, from % Risk, and SL distance.
Attached Files
File Type: mq4 lot size calc.mq4   2 KB | 189 downloads
File Type: mq4 Lot_size_calc_v2.mq4   6 KB | 196 downloads
  • Post #9
  • Quote
  • Last Post: Dec 25, 2019 3:27pm Dec 25, 2019 3:27pm
Quoting emmzett
{quote} Looking at the general approach the first one is "better" because more exact. "Better" in quotes because both may return invalid results. Both approaches miss a final NormalizeDouble(). Also it's recommended to move the min/max evaluation out of the formula and apply it in your strategy logic. Otherwise sooner or later you will experience surprises. A better general function looks like this: /** * Round a lot size according to the specified symbol's lot step value (MODE_LOTSTEP). * * @param double lots - lot size * @param string symbol [optional]...
https://github.com/rosasurfer
you are really great programmer
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