The 3 Sounds of -S Endings: Complete Pronunciation Guide

Published on February 4, 2026

When you add -s or -es to English words (for plurals or third-person verbs), the ending doesn't always sound the same. In fact, there are three different pronunciations: /s/, /z/, and /ɪz/.

For Spanish and Portuguese speakers, this is particularly challenging because in both languages, the letter 's' almost always makes the same sound. In English, however, the pronunciation depends on the final sound of the base word.

The Three -S Sounds

The -s ending is pronounced in three different ways:

  1. /s/ - a soft hissing sound (like in "sun")
  2. /z/ - a buzzing sound (like in "zoo")
  3. /ɪz/ - adds an extra syllable, sounds like "iz"

The key to knowing which sound to use is the final sound of the base word (before adding -s).

Rule 1: The /s/ Sound

Use /s/ when the base word ends in a voiceless consonant sound.

Voiceless consonants are: /p/, /t/, /k/, /f/, /θ/ (th as in "think")

When you make these sounds, your vocal cords don't vibrate. Put your hand on your throat and say "ffff" vs "vvvv" and you'll feel the difference!

Examples with /s/:

Rule 2: The /z/ Sound

Use /z/ when the base word ends in a voiced consonant sound or a vowel sound.

Voiced consonants include: /b/, /d/, /g/, /v/, /ð/ (th as in "this"), /m/, /n/, /ŋ/ (ng), /l/, /r/

All vowel sounds are voiced, so words ending in vowels also take /z/.

This is where Spanish and Portuguese speakers make the most mistakes! Words like "dogs," "cars," and "plays" should have a buzzing /z/ sound at the end, not a hissing /s/.

Examples with /z/:

Rule 3: The /ɪz/ Sound (Extra Syllable)

Use /ɪz/ when the base word ends in a sibilant sound.

Sibilant sounds are: /s/, /z/, /ʃ/ (sh), /ʒ/ (measure), /tʃ/ (ch), /dʒ/ (j)

These are "hissing" or "buzzing" sounds. Adding just -s would make the word impossible to pronounce clearly, so we add an extra syllable.

Examples with /ɪz/:

Quick Reference Chart

Final Sound of Base Word-S PronunciationExamples
Voiceless: /p/, /t/, /k/, /f/, /θ//s/cats, stops, books
Voiced consonants + vowels/z/dogs, cars, plays
Sibilants: /s/, /z/, /ʃ/, /ʒ/, /tʃ/, /dʒ//ɪz/ (extra syllable)buses, watches, boxes

Why This Matters for Spanish/Portuguese Speakers

In Spanish and Portuguese, the letter 's' almost always makes the same /s/ sound. This habit transfers to English, causing several problems:

Common Mistake 1: Using /s/ Instead of /z/

  • Wrong: "dogs" pronounced as /dɔɡs/
  • Right: "dogs" pronounced as /dɔɡz/

When you say "dogs" with /s/, it sounds unnatural and can even be confused with other words.

Common Mistake 2: Forgetting the Extra Syllable

  • Wrong: "buses" as one syllable /bʌss/
  • Right: "buses" as two syllables /ˈbʌsɪz/

Remember, words ending in sibilant sounds always add a full syllable.

Common Mistake 3: Dropping the -S Entirely

Some learners avoid the difficulty by dropping the -s sound altogether. This causes grammar confusion because listeners can't tell if you mean singular or plural.

The Voicing Test

Not sure if a sound is voiced or voiceless? Try this simple test:

  1. Put your fingers on your throat
  2. Make the final sound of the word (not the letter, the sound!)
  3. If you feel vibration, it's voiced (use /z/)
  4. If there's no vibration, it's voiceless (use /s/)

Try it with these pairs:

  • /f/ (no vibration) vs /v/ (vibration)
  • /t/ (no vibration) vs /d/ (vibration)
  • /k/ (no vibration) vs /g/ (vibration)

Practice Sentences

Read these sentences aloud, paying careful attention to each -s ending:

  1. /s/ endings: "The cats climb the roofs and chase rats."
  2. /z/ endings: "She plays with her dogs and runs through the hills."
  3. /ɪz/ endings: "He watches the buses pass by the churches."
  4. Mixed: "My friends (/z/) ride bikes (/s/) to different places (/ɪz/)."

Minimal Pairs Practice

These word pairs differ only in the final -s sound. Practice hearing and producing the difference:

Memory Trick

Here's an easy way to remember the rules:

  • If it hisses or buzzes (/s/, /z/, /ʃ/, /tʃ/, /dʒ/) → add /ɪz/
  • If it's quiet (voiceless) → add quiet /s/
  • If it's loud (voiced) → add loud /z/

Or think of it this way: voiced sounds attract voiced endings. The /z/ sound is voiced, so it naturally follows other voiced sounds.

Common Words to Practice

Here are high-frequency words organized by their -s pronunciation:

Words with /s/:

cats, cups, streets, talks, wants, helps, gets, puts, hits, cuts, sits, waits, eats, meets, writes

Words with /z/:

dogs, cars, boys, girls, friends, names, things, days, ways, times, rooms, doors, words, years, eyes

Words with /ɪz/:

buses, boxes, glasses, classes, watches, teaches, changes, places, faces, houses, uses, causes, closes

Why Getting This Right Improves Your English

Mastering the three -s sounds will:

  • Make you clearer: Native speakers understand you better
  • Sound more natural: You'll avoid the "foreign accent" associated with always using /s/
  • Improve listening: Once you produce these sounds correctly, you'll hear them more easily
  • Build confidence: Speaking correctly feels good!

Practice these patterns until they become automatic. Start slowly, focus on the final sounds, and gradually speed up. With consistent practice, you'll master this essential English pronunciation pattern!


Sources

  • Phonetics Reference
    • Roach, P. (2009). English Phonetics and Phonology: A Practical Course. Cambridge University Press.
  • ESL Teaching Resources
    • Celce-Murcia, M., Brinton, D., & Goodwin, J. (2010). Teaching Pronunciation: A Course Book and Reference Guide. Cambridge University Press.