Estonia has the euro € as its sole currency along with 24 other countries that use this common European money. These 24 countries are: Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia and Spain official euro members which are all European Union member states as well as Andorra, Kosovo, Monaco, Montenegro, San Marino and the Vatican which use it without having a say in eurozone affairs and without being European Union members. Together, these countries have a population of more than 330 million.
One euro is divided into 100 cents. While each official euro member as well as Monaco, San Marino and Vatican issues its own coins with a unique obverse, the reverse, as well as all bank notes, look the same throughout the eurozone. Every coin is legal tender in any of the eurozone countries.
The Estonian kroon EEK ceased to be legal tender on January 15, 2011, but any kroons you have left over can be changed into euros at the Bank of Estonia (http://www.eestipank.ee) at a fixed rate of 15.6466 kroon to €1.
ATMs and currency exchange offices valuutavahetus are widely available. You will get the best rates by exchanging only after arrival in Estonia. Avoid changing money in the airport or port as the rates are lower.