The irrevocable conversion rates in Euro for each participating currency are adopted by the EU Council. They are used for conversion between the Euro and the national currency units and among the national currency units.
On 31 December 1998, and effective from 1 January 1999, the irrevocable conversion rates for the first eleven participating currencies were adopted.
The irrevocable conversion rate for the Greek Drachma was adopted on 1 January 2001, the one for the Slovenian Tolar on 1 January 2007 and the ones for the Cyprus Pound and the Maltese Lira on 1 January 2008.
The irrevocable conversion rate for the Slovak koruna was adopted on 1 January 2009.
The irrevocable conversion rate for the Estonian kroon was adopted on 1 January 2011.