Twenty-one EU members use the euro as their only currency
The euro area is the group of European Union members that have replaced their national currencies with the euro. It has 21 members as of 28 September 2026. The euro began on 1 January 1999 with eleven countries, and members have joined in ones and twos since then, the most recent on 1 January 2026. Six EU members still keep their own currencies. A few countries outside the EU also use the euro, but they are not part of the euro area and are not counted here.
Name them all first. Then sort them by the period in which each adopted the euro.