How much money is there in the world?

To make this question answerable in a finite amount of time, let's simplify things and ask, "How much money is there in actual United States dollars?" Since the statistics for the U.S. are easy to come by, we can examine this question in a couple of different ways.

The first way to look at it might be, "How much cash is there in U.S. currency?" If you took all the bills and coins floating around today and added them all up, how much money would you have? All of that hard and easily liquidated currency is known as the M0 money supply. This includes the bills and coins in people's pockets and mattresses, the money on hand in bank vaults and all of the deposits those banks have at reserve banks [source: Hamilton]. According to the Federal Reserve, there was $908.6 billion in the M0 supply stream as of July 2009 [source: Federal Reserve]. That sounds like an incredible amount, but think about it this way: According to the CIA, there were 307,212,123 Americans alive that month [source: CIA]. If you took all the cash and divided it up equally, each person should have about $3,000 in cash on them (or stuffed under the mattress). Obviously, there's some money missing, but there's an easy explanation for that: The Federal Reserve says that at any given time, between one-half and two-thirds of the M0 money stock of U.S. dollars is held overseas [source: Federal Reserve].

The rest of the money is held in bank accounts of various types, and the Federal Reserve tracks these funds in three different values known as the M1, M2 and M3 money supplies:

M1 represents all of the currency in the M0 money supply, plus all of the money held in checking accounts and other checkable accounts, as well as all of the money in travelers' checks. In July 2009, the M1 money supply for U.S. dollars equaled about $1,655.6 billion [source: Federal Reserve].

M2 is the M1 supply, plus all of the money held in money market funds, savings accounts and small CDs. In July 2009, the M2 money supply was about $8,326.8 billion [source: Federal Reserve].

M3 is M2 plus all of the large CDs. As of March 2006, the Fed no longer tracks the M3 money stock as an economic indicator. That month, M3 totaled around $10.3 trillion [source: St. Louis Fed].

All told, anyone looking for all of the U.S. dollars in the world in July 2009 could expect to find around $8.3 trillion in existence.

Even though the Fed can't say precisely where all the U.S. dollars are in the world, it does try to keep track of how much exists. Not every nation in the world has a well-established central bank, though. Find out why it's so difficult to track exactly how much money exists in the world on the next page.

The Difficulty of Tracking Cold, Hard Cash

When a federal government finds itself in a bind, it's usually tempted to mint its way out of trouble. Printing money can easily solve many spending problems. While it can help in the short term, it does tend to present enormous long-term problems. The Zimbabwean dollar is an excellent recent example of this phenomenon.

In 2000, an exodus of much of Zimbabwe's labor pool led to a collapse of the country's financial system. To support public project spending, the government finance ministry printed surplus Zimdollars -- too many, in fact. Economically speaking, money is like any other commodity: It loses its value when there's an abundance of it. A surplus of readily available money in circulation leads to inflation, where money has less purchasing power. In the first decade of the 21st century, Zimbabwe's economy entered hyperinflation. Economists watching the startling loss of value of the Zimbabwe dollar estimated that it was losing value so quickly that its decline was equivalent to prices doubling in stores every 1.3 days. This puts the annual inflation rate Zimbabwe experienced by the end of 2008 at 516,000,000,000,000,000,000 (quintillion) percent [source: Berger].

The Zimbabwean government decided to fight fire with fire and printed even more money in higher denominations. Eventually, the country would produce a $100 trillion Zimbabwean dollar note -- which had an exchange rate of about 30 U.S. dollars (USD) in January 2009 [source: BBC]. The government would go on to abandon its currency entirely, opting instead to adopt the U.S. dollar and South African rand as official currencies.

But what about all those trillion-dollar notes that the country's finance ministry produced in 2008? Zimbabwe shows how difficult it can be to keep track of how much money a single nation has in the global markets, let alone how much money there is in the world.

However, this inherent difficulty hasn't stopped some from trying. Perhaps the closest estimate to how much money exists in the world was released in January 2009 by Mike Hewitt, editor of the economics blog DollarDaze.com. Hewitt tracked the reporting of 73 currencies from central banks and financial ministries in 90 countries, which cover the money used by 84.1 percent of the world's population. The countries tracked represent 96.7 percent of the world gross domestic product -- the market value of the world's economies combined. Hewitt found that in October 2008, these countries had notes and coins equaling $3.94 trillion in U.S. dollars in circulation [source: Hewitt]. That's a lot of moolah.

Things would be a lot easier on Mike Hewitt and foreign exchange market analysts if there was only a single currency used by every country on the planet. So why don't we?