Count syllables in a word or sentence.
Syllable counting works by identifying vowel groups, since each syllable has exactly one vowel nucleus and consecutive vowels usually form a single diphthong rather than two syllables. Two adjustments handle the main English irregularities. A trailing e is usually silent — make and time are one syllable each — so it is stripped by default. But the consonant-plus-le ending does form its own syllable, so table and simple are two. This approach is accurate to within a few percent on ordinary prose, though it under-counts unusual words and proper nouns, which is why an override for silent e is offered.
Vowel group method
Syllables = number of consecutive vowel groups, minimum 1 per word
English adjustments
Strip a trailing silent e; treat a consonant followed by -le as its own syllable
Because English spelling maps irregularly onto pronunciation, and syllabification varies by accent — fire is one syllable for some speakers and two for others. A vowel-group algorithm handles regular words well but cannot resolve genuinely ambiguous cases or unfamiliar proper nouns.
Readability formulas use average syllables per word as a proxy for word difficulty, which is why Flesch scores need it. Poets need it for metre, particularly fixed forms like haiku. Songwriters use it to fit lyrics to a melody, where syllables map to note positions.