Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
Capacity is regular. It follows the -ies Conversion rule.
Use plural verbs: "The capacities are ready" (not "is ready").
Yes. The plural capacities is standard across all English variants.
The word capacity follows the standard English pluralization rule. When forming the plural, capacity becomes capacities. This follows the -ies Conversion pattern, which is one of the most common plural rules in English.
Understanding why capacity becomes capacities helps with spelling and pronunciation. Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
When using capacities in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The capacities are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.