Prominent websites such as Bloomberg.com, MarketWatch.com and BarChart.com feature free, interactive dollar index charts that generate both past and present statistics. The U.S. dollar index (often abbreviated as USDX) measures the value of the U.S. dollar against six other currencies that it trades with the most.
The euro, the Japanese yen, the British pound, the Canadian dollar, the Swedish krona and the Swiss franc are the six currencies against which the U.S. dollar is measured. The index rating goes up when the U.S. dollar becomes more valuable compared to its competitors. The index gets updated from Sunday evening until Friday afternoon while U.S. markets are active.