The Estonian language is rich in vowels: the vowel-consonant rate in Estonian is 45:55; the 26 Estonian phonemes include 9 vowels: u, o, a, õ, ü, ö, ä, e, i (the inhabitants of the western part of the largest island Saaremaa use only eight vowels, though, replacing õ with ö. Võro-speakers of the southeast have ten, since they use two distinct õ-s.) As many as 36 diphthongs can be formed from vowels that offer interesting combinations (e.g. the compound word kõueööaimdus 'anticipation of the thundery night'). Vowels on their own can also carry a meaning: öö 'night', õu 'backyard', ei 'no'. Some Estonian compounds may even have quadruplicate vowels, for example: Kuuuurijate töööö jäääärel, 'A moon researchers' work-night at the edge of the ice'.

The Estonian language does not like consonant clusters, especially the initial ones. These became established in Estonian mainly through loan words, i.e. tross 'cable', kross, German 'Groschen', etc. The later word-interior vowel disappearance - syncope - resulted in numerous consonant clusters, even in native Estonian words. Consonant clusters mostly consist of two consonants, but in the word vintsklema 'to writhe', for instance, there are five consonants in a row.

A few exceptions excluded, the main stress in Estonian words falls on the first syllable, the frequent secondary stress on odd, non-final syllables.