Plural nouns

When you're talking about more than one of something, English nouns usually change form — this is called the plural. Most of the time it's as simple as adding -s: one cat, two cats. But a few common nouns change in their own special way, and those are worth learning by heart.

Quick shortcut: most nouns just add -s. A handful of very common ones — like child, man, and mouse — don't follow that pattern at all, so it's worth memorizing them separately.

The basic rule: add -s

For most nouns, you simply add -s to the singular form:

• cat → cats
• book → books
• table → tables
• day → days

Common spelling patterns in plurals

A few spelling patterns change slightly when you add the plural ending. Some are predictable from spelling, and a few common words just need to be learned individually.

Words ending in -s, -ss, -sh, -ch, -x, -z: add -es

Most everyday nouns with these endings add a full extra syllable, -es, to make the plural easier to say:

• bus → buses
• class → classes
• brush → brushes
• watch → watches
• box → boxes
• buzz → buzzes

A few -ch words have a hard k sound instead, so they just add -s: ✅ stomach → stomachs, ✅ monarch → monarchs.

Some short -z words double the z before adding -es, especially common ones like quiz → quizzes.

(A few less common, more formal words borrowed from Latin or Greek — like analysis → analyses or crisis → crises — have their own special plurals. Those are worth learning separately when you meet them.)

Consonant + -y: change to -ies

If a noun ends in a consonant followed by -y, the y changes to i before adding -es:

• city → cities
• baby → babies
• story → stories

If the letter before the -y is a vowel, nothing changes — just add -s: ✅ boy → boys, ✅ day → days, never ❌ boies or ❌ daies.

Some words ending in -f or -fe: change to -ves

A number of common nouns ending in -f or -fe swap that ending for -ves:

• knife → knives
• life → lives
• wife → wives
• leaf → leaves
• shelf → shelves

This doesn't happen to every -f word, though — some just add -s as normal: ✅ roof → roofs, ✅ cliff → cliffs, ✅ chief → chiefs.

Some words ending in consonant + -o: add -es

Some common nouns ending in a consonant + -o add -es instead of just -s:

• potato → potatoes
• tomato → tomatoes
• hero → heroes

But many other -o words just add -s: ✅ photo → photos, ✅ piano → pianos, ✅ kilo → kilos. There's no fully reliable rule here — the safest approach is to learn the common -oes words individually.

Irregular plurals

Some of the most frequently used English nouns don't follow the -s rule at all — the whole word changes instead. These are worth memorizing, since they show up constantly in everyday speech:

✅ I have two children. — never ❌ I have two childs. ✅ There are three mice in the kitchen. — never ❌ three mouses.

(You might also see persons on a formal sign, like "Maximum 10 persons" — but people is the one to use in everyday speech.)

Nouns that don't change in the plural

A small group of nouns look exactly the same in the singular and the plural — you can only tell which one is meant from the rest of the sentence (a number, a/an, or the verb):

• sheep → sheep: one sheep, three sheep
• fish → fish: one fish, many fish
• deer → deer: a deer, five deer

✅ I saw two sheep in the field. — never ❌ two sheeps.

Common mistakes

• ❌ I have two childs. → ✅ I have two children. (irregular plural)
• ❌ Three mans are waiting. → ✅ Three men are waiting. (irregular plural)
• ❌ There are many peoples here. → ✅ There are many people here. (people is already the everyday plural of person — peoples is a different word, meaning different ethnic or national groups)
• ❌ I need two knifes. → ✅ I need two knives. (-fe → -ves)
• ❌ How many citys are there? → ✅ How many cities are there? (consonant + -y → -ies)
• ❌ We saw five sheeps. → ✅ We saw five sheep. (no change in the plural)
• ❌ She has two boxs. → ✅ She has two boxes. (-x → -es)

Quick check

What's the plural?

1. dog → ____
2. city → ____
3. child → ____
4. knife → ____
5. sheep → ____
6. box → ____

Key takeaways

• Most nouns form the plural by simply adding -s: cat → cats.
• Nouns ending in -s, -ss, -sh, -ch, -x, -z add -es; a consonant + -y changes to -ies; some -f/-fe words change to -ves.
• A small set of very common nouns are irregular and just have to be learned: child → children, man → men, mouse → mice, person → people.
• A few nouns, like sheep and fish, look the same in the singular and the plural.