Currencies of the European Union

There are eleven currencies of the European Union as of 2015^[update], the principal currency being the Euro. The Euro is used by the institutions of the European Union and by the Eurozone states, which account for 19 of the 28 member states of the European Union. All but two states are obliged to adopt the currency; Denmark and the United Kingdom, through a legal opt-out from the EU treaties, have retained the right to operate independent currencies within the European Union. The remaining eight states must join the ERM II and attain the third stage and adopt the Euro eventually.

The euro is the result of the European Union's project for economic and monetary union which came fully into being on 1 January 2002. and it is now the currency used by the majority of European Union's member states, with all but three bound to adopt it. It is the currency used by the institutions of the European Union and in the failed European Constitution it was to be included with the symbols of Europe as the formal currency of the European Union. The euro is also widely used by other states outside the EU.

Reinhart and Rogoff classifies the exchange rate regimes of EU countries as follows:

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