Macro & Central BanksPPPLaw of One Price
Purchasing Power Parity (PPP)
The theory that exchange rates should adjust so that a basket of goods costs the same across countries once converted into a common currency.
What Purchasing Power Parity (PPP) means
Purchasing power parity holds that, in the absence of transport costs and trade barriers, identical goods should cost the same everywhere once prices are converted at the prevailing exchange rate. In its absolute form it implies a level for the exchange rate derived from national price levels; in its relative form, which is more defensible, it implies that a currency should depreciate over time at roughly the difference between its inflation rate and its trading partner's. Informal versions, such as comparing the price of a single standardised burger internationally, illustrate the same idea.
For traders, purchasing power parity is a long-horizon anchor rather than a trading signal. Empirically, deviations from it are large and persist for years, because many goods and most services are not traded across borders, productivity differs between economies, and capital flows dominate trade flows in setting short-run exchange rates. It is most useful for judging whether a currency is stretched relative to its long-run value, and for the fair-value estimates that underpin multi-year strategic positioning.
Worked example
If a basket costs 100 dollars in the United States and 95 euros in the euro area, purchasing power parity implies a rate near 1.0530, so a spot rate around 1.0850 would suggest the euro is trading above that anchor. Illustrative calculation only.
Related terms
- Interest Rate ParityThe no-arbitrage relationship linking spot and forward exchange rates to the interest rate differential between two currencies.
- InflationA sustained increase in the general price level, which erodes the purchasing power of a currency over time.
- Trade BalanceThe difference between the value of a country's exports and its imports of goods and services over a period.
- Currency PegAn arrangement in which a country fixes its currency's value to another currency or basket, defended by the monetary authority.
Frequently asked questions
What does Purchasing Power Parity (PPP) mean in forex trading?
The theory that exchange rates should adjust so that a basket of goods costs the same across countries once converted into a common currency.
How does Purchasing Power Parity (PPP) work in practice?
For traders, purchasing power parity is a long-horizon anchor rather than a trading signal. Empirically, deviations from it are large and persist for years, because many goods and most services are not traded across borders, productivity differs between economies, and capital flows dominate trade flows in setting short-run exchange rates. It is most useful for judging whether a currency is stretched relative to its long-run value, and for the fair-value estimates that underpin multi-year strategic positioning.
What is an example of Purchasing Power Parity (PPP)?
If a basket costs 100 dollars in the United States and 95 euros in the euro area, purchasing power parity implies a rate near 1.0530, so a spot rate around 1.0850 would suggest the euro is trading above that anchor. Illustrative calculation only.
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