Spelling Tips: The “Y” to “I” Rule

When a word ends in a vowel plus “-y,” it’s usually easy to modify it by adding a letter (or letters): adding “-ous,” for example, means “joy” becomes “joyous.”

However, when a word ends in a consonant plus “y” things get more complicated, which can make spelling challenging. To ensure your written work is error-free, it helps to keep the “y” to “i” rule in mind.

The “Y” to “I” Rule

The basic rule is, for any word that ends in a consonant plus “-y,” change the “y” to “i” if adding a suffix or forming a plural.

Plurals

For plurals, simply change the “y” to an “-ies”:

First-Person Singular and Past Tense Verbs

Forming the first-person singular of a verb ending in a consonant plus “y” requires changing the “y” to “-ies.” while the past tense involves switching “y” for “-ied”:

Comparatives and Superlatives

When an adjective ends in a consonant plus “-y,” forming a comparative or superlative involves changing the “y” to “-ier” and “-iest” respectively:

Forming Adverbs

Modifying an adjective to make an adverb involves substituting the “y” for “-ily”:

Exceptions

The “y”-to-“i” rule doesn’t always work; some variations of “sly,” for example, can be spelled with either a “y” or an “i” (e.g., “slyest/sliest” and “slyer/slier”).

Moreover, while changing “y” to “i” isn’t typically necessary when a word ends with a vowel plus “-y,” there are exceptions here too (such as modifying “day” to become “daily”).

As such, although the “y” to “i” rule is a good guideline, it’s still important to double-check words if you’re not sure they’re spelled correctly.