im guessing he's going to say it depends on how much money is in the account. in the emini futures its your account size devided by the brokers margin. if the brokers margin is $500 and you have $5,000 in your account, if your stupid enough you could trade 10 contracts. every broker/fcm has a different margin for day trading. when you hold contracts overnight, margins get very standard between the fcm's. im sure it very similiar for the forex. though i don't know that for sure.