Sound Gym
cost · coast
Short /ɒ/ versus diphthong /oʊ/ — and a silent letter A in coast to watch for.
Cost: short clipped /ɒ/ — mouth opens and snaps shut. Coast: a diphthong /oʊ/ — lips glide and move throughout the vowel. Important for Arabic and Japanese speakers.
mouth shape
mouth open, short clipped /ɒ/ — stops quickly at the end
cost
/kɒst/
vowel length
mouth shape
lips glide from /o/ to /ʊ/ — two-sound vowel, mouth moves
coast
/koʊst/
vowel length
Key difference
Put your finger on your lips — for cost, your lips barely move. For coast, your lips start slightly open and push forward into a rounded position. The vowel in coast is longer and keeps moving.
Hear it in a sentence
“The cost of renting a flat in London has risen sharply this year.”
“We drove along the coast road until we found a quiet beach.”
Hear it in the wild
Real speech from native speakers — the most reliable way to check a pronunciation, since automated audio can vary by device and browser.
cost
Hear native speakers say “cost” in real sentences — news, lectures, and podcasts.
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coast
Hear native speakers say “coast” in real sentences — news, lectures, and podcasts.
Opens YouTube-sourced clips in a new tab.
How teachers explain this
Approved tips from the community, sorted by helpfulness
Spelling note
coast contains a silent letter A — the spelling is c‑o‑a‑s‑t but the A makes no sound. The letters oa together spell one diphthong /oʊ/.
Word families
cost family ▸
coast family ▸
Related pairs
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