The Letter X: The /ks/ vs /ɡz/ Rule Almost No One Teaches

The letter X is a shape-shifter. It can sound like /ks/, /ɡz/, /z/, or even /kʃ/, and the choice is not random — it follows stress. Once you see the pattern, X stops being a mystery.

The Four-Sound Rule

1. /ks/: when followed by a consonant or a syllable with an unstressed vowel: exit, box, fix, extreme.
2. /ɡz/: when the next syllable begins with a stressed vowel (or silent H + vowel): exam, exact, exhaust.
3. /z/: at the start of a word (Greek roots): xylophone, xenon.
4. /kʃ/: before U/I + vowel (palatalization): luxury, anxious.

X = /ks/ (Default)

X = /ɡz/ (Before Stressed Vowel)

X = /z/ (Greek Initial)

Why ex- is Sometimes /ks/ and Sometimes /ɡz/

Read the stress pattern first; the X follows automatically.

Bonus: X = /kʃ/

Before u or i plus another vowel, /ks/ palatalizes to /kʃ/:

• luxury /ˈlʌkʃəri/
• anxious /ˈæŋkʃəs/
• complexion /kəmˈplɛkʃən/

Exceptions and Oddities

• anxiety /æŋˈzaɪəti/ uses /ŋz/, not /ks/ or /ɡz/.
• Texas /ˈtɛksəs/ keeps /ks/ — the next vowel is unstressed.
• x-ray /ˈɛksreɪ/ stays /ks/ because it is a compound, not a Greek root.

Key Takeaways

1. /ks/ is the default; /ɡz/ happens before a stressed vowel.
2. Word-initial X from Greek is /z/.
3. X + U/I + vowel becomes /kʃ/.
4. Stress predicts the sound.