Velocity of money
The term "velocity of money" (also "velocity of circulation of money") refers to how fast money passes from one holder to the next. It can refer to the income velocity of money, which is the frequency at which the average unit of currency is used to purchase newly domestically-produced goods and services within a given time period. In other words, it is the number of times one unit of money is spent to buy goods and services per unit of time. Alternatively and less frequently, it can refer to the transactions velocity of money, which is the frequency with which the average unit of currency is used in any kind of transaction in which it changes possession—not only the purchase of newly produced goods, but also the purchase of financial assets and other items.
If the velocity of money is increasing, then transactions are occurring between individuals more frequently. Although once thought to be constant, it is now understood that the velocity of money changes over time and is influenced by a variety of factors.
If, for example, in a very small economy, a farmer and a mechanic, with just $50 between them, buy new goods and services from each other in just three transactions over the course of a year
then $100 changed hands in the course of a year, even though there is only $50 in this little economy. That $100 level is possible because each dollar was spent on new goods and services an average of twice a year, which is to say that the velocity was . Note that if the farmer bought a used tractor from the mechanic or made a gift to the mechanic, it would not go into the numerator of velocity because that transaction would not be part of this tiny economy's gross domestic product (GDP).
The velocity of money provides another perspective on money demand. Given the nominal flow of transactions using money, if the interest rate on alternative financial assets is high, people will not want to hold much money relative to the quantity of their transactions—they try to exchange it fast for goods or other financial assets, and money is said to "burn a hole in their pocket" and velocity is high. This situation is precisely one of money demand being low. Conversely, with a low opportunity cost velocity is low and money demand is high. In money market equilibrium, some economic variables (interest rates, income, or the price level) have adjusted to equate money demand and money supply.
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