Real effective exchange rate (REER)

The real effective exchange rate (REER) measures a currency's value against a basket of its trading partners' currencies, weighted by trade volume, and adjusted for differences in inflation between countries. It answers a broader question than a single bilateral exchange rate: is this currency expensive or cheap relative to the countries it actually trades with, once price-level differences are stripped out.

REER is built in two steps: first a nominal effective exchange rate is calculated as a trade-weighted average of bilateral rates, then that average is adjusted by relative consumer prices, roughly REER = NEER × (domestic price level / weighted foreign price level). A rising REER means a currency is becoming more expensive in real terms against its trading partners, which can erode export competitiveness even if the currency looks stable against any single peer. This is the practical, current-state cousin of purchasing power parity, which is a theory about where exchange rates should head rather than a measure of today's deviation.

Central banks, trade economists, and macro investors watch REER as a competitiveness gauge and an input to currency valuation, often alongside the consumer price index data used to build it. A common pitfall is comparing REER levels across different index providers or base years directly, since the trade weights, currency basket, and base period differ by source and are not standardized.