Purchasing Power Parity Calculator
Purchasing Power Parity (PPP) is the exchange rate that would make the price of an identical good or basket of goods equal across two countries. The PPP-implied exchange rate is simply the ratio of prices: price in country A divided by price in country B (both in local currency). If the market rate differs from the PPP rate, one currency is over- or under-valued relative to the other on a PPP basis. Enter the price of a comparable good in each country and the current market exchange rate to see the PPP rate and the over- or under-valuation percentage.
PPP formula
PPP rate (A/B) = price in A / price in B
Deviation% = (market rate - PPP rate) / PPP rate x 100
Positive deviation: currency B is overvalued vs PPP
Negative deviation: currency B is undervalued vs PPP
This is the absolute PPP or law-of-one-price formulation. The OECD and World Bank use a more comprehensive basket of hundreds of goods to produce official PPP conversion factors.
Uses of PPP exchange rates
- International GDP comparisons: World Bank Atlas method uses PPP to convert GDPs to a common standard.
- Expat salary benchmarking: PPP rates help determine whether an overseas salary offers comparable purchasing power.
- Transfer pricing: multinational firms use PPP as one benchmark for intercompany pricing.
- Currency valuation models: PPP is a long-run anchor in exchange rate forecasting models.
Frequently asked questions
What is Purchasing Power Parity?
Purchasing Power Parity (PPP) is an economic theory that states, in the long run, exchange rates should adjust so that an identical basket of goods costs the same in any two countries when prices are expressed in a common currency. It is used to compare real GDP and living standards across countries.
How is the PPP exchange rate calculated?
PPP rate = price of good in country A / price of the same good in country B, both expressed in their respective local currencies. If a burger costs $5.00 in the US and 4.50 GBP in the UK, the PPP rate is 5.00 / 4.50 = 1.11 USD per GBP.
Where does the OECD get PPP data?
The OECD and World Bank publish official PPP conversion factors derived from the International Comparison Program (ICP), which collects prices for hundreds of goods and services across member countries. These are published annually at data.oecd.org and data.worldbank.org.
Why does the PPP rate differ from the market exchange rate?
Market rates reflect capital flows, trade balances, and speculation in the short run. PPP rates reflect relative price levels and tend to converge with market rates only over very long time periods. Non-traded services (like haircuts) are systematically cheaper in lower-income countries.
What is the Big Mac Index?
The Big Mac Index, published by The Economist, is an informal PPP guide using the price of a McDonald's Big Mac as a proxy for a comparable good. It is a simplified illustration of PPP theory, not an official measure.
Official sources
- OECD Purchasing Power Parities: data.oecd.org.
- World Bank International Comparison Program: worldbank.org/en/programs/icp.
- Federal Reserve Foreign Exchange Rates: federalreserve.gov/releases/h10/.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.