If a word ends in ‑s, ‑sh, ‑ch, ‑x, or ‑z, you add ‑es. For almost all other nouns, add -s to pluralize.
How to Spell Plural Nouns: With -es or -s?
When do you add ‑s and when do you add ‑es to make a plural noun? It’s not quite as arbitrary as it may seem.
If a word ends in ‑s, ‑sh, ‑ch, ‑x, or ‑z, you add ‑es. Consider the examples below:
I had to take only one bus; you had to take two buses.