The equation of exchange and velocity of money
The quantity theory of money rests on the equation of exchange, which links money supply, how fast money circulates, the price level, and real economic output. This calculator solves for any one variable when you know the other three. All math runs in your browser.
Central banks and economists track velocity to understand whether expanding the money supply translates into higher spending or sits idle in balances. To break M0, M1, M2, and M3 into component aggregates, use the money supply calculator. To see how rising prices erode purchasing power over time, pair this with the inflation calculator. When comparing nominal GDP to inflation-adjusted output, the GDP deflator calculator converts between current and constant-dollar measures.
MV = PY formula
- M: Money supply (currency plus deposits in circulation)
- V: Velocity of money (how many times each dollar is spent per period)
- P: Price level or price index
- Y: Real GDP or real output
The right side, P × Y, equals nominal GDP: total spending at current prices. Rearranging the identity gives the four solution forms used by this tool:
Worked example: solving for velocity
Suppose money supply M = $2 trillion, price level P = 1.2, and real GDP Y = $2.5 trillion. Nominal GDP is P × Y = $3 trillion. Velocity is:
Each dollar in circulation supports $1.50 of nominal spending in that period. The Federal Reserve notes that velocity tends to fall during recessions when households and firms hold more cash and reduce transactions. The spending multiplier calculator models how an initial spending shock propagates through the economy via successive rounds of consumption.
Frequently asked questions
What does velocity of money measure?
Why did U.S. velocity decline after 2008?
Is nominal GDP always equal to M × V?
What units should I use for M and Y?
Can I solve for price level instead of velocity?
Are my inputs saved on a server?
Resources and references
The formulas and methods in this calculator were checked against these independent sources.