There are various estimates, since the exact amount of US currency gets estimated differently. Assuming "currency" means federal reserve notes and coins used as legal tender, the best guess is about $829 billion dollars. However, that number increases frequently. It is estimated that well over one-half of US currency is held in countries other than the United States. Most "money" is actually "created" as electronic transfers between banks and does not rely on physical paper money at all. Roughly 80 percent of all financial transactions, in terms of dollar amount (not number of transactions), are handled that way.