The U.S. Dollar Index (DXY) measures the value of the U.S. dollar relative to a basket of major foreign currencies. Traders and economists widely use it to gauge the dollar’s overall strength in global markets. The index was introduced in 1973 after the collapse of the Bretton Woods system, when currencies began to float freely.

The DXY is calculated using a weighted geometric mean of six currencies: the euro (EUR), Japanese yen (JPY), British pound (GBP), Canadian dollar (CAD), Swedish krona (SEK), and Swiss franc (CHF). Among these, the euro carries the largest weight, around 57.6%, making it the most influential component of the index. Each currency’s weight reflects its importance in U.S. trade at the time the index was created.

Mathematically, the index uses a formula that applies specific exponents (weights) to each currency exchange rate relative to the dollar. When the U.S. dollar strengthens against these currencies, the DXY rises; when it weakens, the index falls. The base value of the index is 100, set in 1973.

Because it reflects global demand for the dollar, the DXY is closely monitored in forex, commodities, and macroeconomic analysis. It also plays a key role in understanding movements in assets like gold, which often show an inverse relationship with the dollar’s strength.