"Of" and "off" look almost identical, but they sound very different. Confusing them is one of the most common mistakes I hear from learners. The good news? The rule is simple once you see it.
The Core Difference
OF is /əv/ (rhymes with love). OFF is /ɔːf/ (rhymes with cough). They differ in BOTH the vowel and the final consonant.
| Word | IPA | Vowel | Final consonant |
|---|---|---|---|
| of | /əv/ | schwa | V (voiced) |
| off | /ɔːf/ | open back /ɔː/ | F (voiceless) |
Why "Of" Sounds Like "Uv"
The letter F in of is the only common English word where F = /v/. Native speakers hear "uv", not "of".
The Reduction Rule
"Of" is a function word — it almost never gets stress. It almost always reduces to /əv/:
- "a piece of cake" → /ə piːs əv keɪk/
- "out of here" → /ˈaʊtə hɪr/ (out-uh)
"Off" is a content word: stressed and clear /ɔːf/.
The "Could Of" Mistake
Because of reduces to /əv/, it sounds exactly like the contraction 've. Native speakers sometimes write "could of" by mistake — but the correct form is could've = could have.
Practice Sentences
- The leaves fell off the tree because of the wind.
- The end of the day, I take off my shoes.
- I'm thinking of taking the day off.
Short, weak, voiced for of; full, clear, voiceless for off.