There are various statistics used to track each country's currency in circulation. The main ones that most people reference are the following: M0: The total of all physical currency, plus accounts at the central bank that can be exchanged for physical currency. M1: The total of all physical currency part of bank reserves + the amount in demand accounts ("checking" or "current" accounts). M2: M1 + most savings accounts, money market accounts, retail money market mutual funds,and small denomination time deposits (certificates of deposit of under $100,000). M3: M2 + all other ...