Esperanto has 22 consonants, 5 vowels, and two semivowels, which combine with the vowels to form 6 diphthongs. (The consonant/j/ and semivowel/i̯/ are both written <j>.) Tone is not used to distinguish meanings of words. Stress is always on the penultimate vowel, unless a final vowel o is elided, a practice which occurs mostly in poetry. For example, familio "family" is stressed IPA: [fa.mi.ˈli.o], but when found without the final o, famili’, the stress does not shift:[fa.mi.ˈli].
Esperanto has the five cardinal vowels of Spanish, Swahili, and Modern Greek.
| Front | Back | |
|---|---|---|
| Close | i | u |
| Mid | e | o |
| Open | a | |
There are six falling diphthongs: uj, oj, ej, aj, aŭ, eŭ (/ui̯, oi̯, ei̯, ai̯, au̯, eu̯/).
With only five vowels, a good deal of variation is tolerated. For instance,/e/ commonly ranges from[e] (French é ) to[ɛ] (French è ). The details often depend on the speaker's native language. A glottal stop may occur between adjacent vowels in some people's speech, especially when the two vowels are the same, as in heroo "hero" ([he.ˈro.o] or[he.ˈro.ʔo]) and praavo "great-grandfather" ([pra.ˈa.vo] or[pra.ˈʔa.vo]).