Inside the order zone, traders may notice that for the same contract quantity, the order cost may differ for a Buy Long and Sell Short direction. There are 2 reasons why. 
 

1) The formula for calculating order cost 

For more information about the formula for calculating order cost, please click here.
In this regard, traders can easily identify that the reason for the difference in order cost between a Buy Long and Sell Short order is due to the bankruptcy price used to calculate the fee to close. 

For example BTCUSD 1000 Contract Quantity at USD 7500 entry price, 20x leverage for both Buy Long and Sell Short direction 

Bankruptcy Price for Buy Long =  7500 x [20/(20+1)] = USD 7143

Bankruptcy Price for Sell Short = 7500 x [20/(20-1)] = USD 7894.50

Fee to close = (Quantity / Bankruptcy Price) x 0.055% 

Note: The fee to close is only an amount of margin set aside by the system to allow the position to close at its theoretical worst case scenario (liquidation executed at bankruptcy price). This is not the absolute final amount that traders will always pay when closing the position. If traders close their position via Take Profit or Stop Loss and there are excess margin leftovers, they will be credited back to the user's available balance.  

2) The input of the order price in a limit order 

For more information about limit orders, please click here.

For this point, it is further broken down into 2 sub-points for better understand. 

a) When order price is placed at a price better than Last Traded Price (Buy Long = Lower, Sell Short = Higher) 

• The system will only use the order price to calculate the fee to open, which in turn affects the overall order cost. 

b) When order price is placed at a price worse than Last Traded Price (Buy Long = Higher, Sell Short = Lower)

• The system will use the best available market price based on the order book to calculate the fee to open, which in turn affects the overall order cost.