Isolate the first line of your poem.
Count the number of vowels in the first word of your poem. Vowels consist of the letters a, e, i, o, u and sometimes y.
Subtract 1 from the number of vowels for every silent vowel. For example, if you have the word "make," you would count the two vowels "a" and "e." Then you would subtract 1 from 2 since the "e" is silent in this word.
Subtract 1 from your previous total if the first word has any double vowels that make a single sound. For example, the word "shoot" has the letter "o" twice, but the vowels make a singular sound. Therefore, this total would be 1.
Take away 1 from your total if any diphthongs are present in the word. A diphthong is a pair of vowels that make one sound. For instance, the word "flour" has two vowels, but the "o" and the "u" make one sound so the total would be 1.
Repeat this procedure for the rest of the words on the first line. Add the total syllables to find the syllable total for the line.
Repeat this process for the following lines of the poem. Many poems feature patterns of syllable totals within their lines. For instance, you might have a five-line poem in which the first, second and fifth lines have 12 syllables, and the third and fourth lines have six syllables each. Make adjustments to your content if you need to add or subtract syllables.