First establish which group is being counted.
A member state is a country belonging to the European Union. The question counts these countries, not members of Parliament, official languages or stars on a flag. The geographical term Europe is also broader than the EU.
The number is not a timeless geographical property. Accessions or withdrawals can change a membership count. That is why an answer to “today” needs a checked date; here, that date is 20 October 2026.

The other three answers
Check each number against the group being asked about and the current date.
21
At the checked date, 21 is the number of EU countries using the euro, not all EU member states. The question names the EU as a whole.
23
23 does not match the current list of 27 EU member states. A number without the correct group of countries is not a sufficient answer.
25
25 is not the present membership count. Earlier configurations must not be adopted as the current answer without checking.
The EU, euro area and Europe are different groups.
Not every EU member currently uses the euro. Conversely, being geographically in Europe does not automatically establish EU membership. Whenever you read a number, check exactly what is being counted.
The United Kingdom left the EU on 31 January 2020. It therefore does not belong to the present list of 27. An older source may describe a different composition; that does not make its historical information current.
The 27 member states · European Union ↗EU members: 27 — checked on 20 October 2026.
Remember the number, group and date together. Do not confuse 27 EU member states with 21 euro-area countries.
Three words for this question
- der Mitgliedstaatmember state
- A country belonging to a particular international organisation or union.
- der Beitrittaccession
- A new member joining.
- der Austrittwithdrawal
- Leaving membership.
