Free margin is the amount of your trade balance that is available for opening new positions. Free margin is calculated as equity minus used margin. With equity of $8,750 and used margin of $2,500 free margin would be $8,750 - $2,500 = $6,250. Note that if you try to open a position for which you do not have sufficient free margin, the order will be automatically cancelled (with the message "Insufficient funds").
