Purchasing Power Parity

Purchasing power parities are statistical conversion factors used to compare quantities of goods and services across economies after adjusting for price-level differences. They differ from market exchange rates and do not imply that currencies can be traded at those factors or that a single item's price should be equal everywhere.

Purchasing power parities are conversion factors for comparing the volume of goods and services across economies with different price levels. They are built from comparisons across many items, not one product. Market exchange rates answer a different question: how currencies can be exchanged for transactions. A PPP factor is not necessarily an available trading rate.

For a person's relocation, a national-average basket may be a poor match to actual housing, care, transport, and imported-goods needs. Use PPP to understand why nominal comparisons can mislead, then build a relevant local basket. PPP-adjusted output also remains an economic aggregate, not a complete measure of welfare, distribution, or a prediction that exchange rates will converge quickly.

When to use it

When interpreting international output or consumption comparisons and understanding how differing price levels affect nominal comparisons.

How it can help

Choose the conversion that matches the question. Use PPP for suitable aggregate volume comparisons, market exchange rates for actual cross-currency payments, and a relevant local basket for personal cost comparisons.