Invalid volume for HSBC but not RBS

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Hi again to this wonderful community!

I'm using this very simple position sizing code to determine how many lots to buy - it began life as a Forex lot sizer, and I'm now trying to use it for stock CFDs, however it seems to only work for some stocks, and generates volume errors when used for others.

When I use it for RBS, it buys lots of 10 or so with a balance of £50,000, and a RiskPercentage of 5%. However when I try to use it to test it with HSBC with all parameters the same other than the instrument in question - it tries to buy "8.333K" which the platform reports is an "invalid volume".

The "lot" variable is an INT, and tickValue and stopInTicks are doubles. I had previously used "lot" as a double, with MathsAbs to effectively remove the decimal points, however it seems to give me the same errors, so I changed it to INT to force it to be modulated effectively.

         tickValue = SymbolInfoDouble(_Symbol, SYMBOL_TRADE_TICK_VALUE);
         stopInTicks = stopLossPips * P * _Point;
         
         lot = MathAbs(RiskPercentage/100) * AccountInfoDouble(ACCOUNT_BALANCE) / (stopInTicks / _Point * tickValue);
         Print ("Current lot size to buy is ",lot);

Help me MQL5.com you're my only hope!


Thanks!!!

 
Never risk more than a small percentage of your account, certainly less than 2% per trade, 6% total to the account. In code (MT4): Risk depends on your initial stop loss, lot size, and the value of the pair. It does not depend on margin and leverage.
  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 You place the stop where it needs to be — where the reason for the trade is no longer valid.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 2017.10.10
              Is there an universal solution for Tick value? - Currency Pairs - General - MQL5 programming forum 2018.02.11
              Lot value calculation off by a factor of 100 - MQL5 programming forum 2019.07.19
  4. You must normalize lots properly and check against min and max.
  5. You must also check FreeMargin to avoid stop out

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.

 
William Roeder:
Never risk more than a small percentage of your account, certainly less than 2% per trade, 6% total to the account. In code (MT 4): Risk depends on your initial stop loss, lot size, and the value of the pair. It does not depend on margin and leverage.
  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 2017.10.10
              Is there an universal solution for Tick value? - Currency Pairs - General - MQL5 programming forum 2018.02.11
              Lot value calculation off by a factor of 100 - MQL5 programming forum 2019.07.19
  4. You must normalize lots properly and check against min and max.
  5. You must also check FreeMargin to avoid stop out

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.

Thanks William, I'll go and read these links today and come back to you! Thank you very much for sharing them, much appreciated!!!


Cheers!

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