Learners often say 'want' with the same A as 'cat', but native speakers do not. The letter W has a hidden power: it reshapes the vowel that comes right after it. Once you see the pattern, a whole group of common words becomes predictable.
The Rule
After W (and often after QU), the letter A usually becomes /ɑː/ (the 'ah' in 'father'), not the expected /æ/ (the 'a' in 'cat'). And the combination WOR becomes /wɜːr/ (like 'were'), while WAR becomes /wɔːr/ (like 'wore'). The lip-rounding of W pulls the vowel backward.
WA usually sounds like /ɑː/ (ah)
WAR = /wɔːr/, WOR = /wɜːr/
Why This Happens
W is made with rounded lips, and that rounding carries into the next vowel, bending it toward a back, rounded shape. This is why 'wash' does not rhyme with 'cash', and 'war' does not rhyme with 'car'. The rule is very reliable for everyday words.
Exceptions to Watch
The pattern breaks when a specific consonant follows the A. Before /k/ or /ɡ/, WA keeps the /æ/ sound: 'wax', 'wag', 'whack', and 'swam' all use /æ/. So the pull happens most strongly before sounds like /ʃ/, /tʃ/, /n/, and /t/.
Practice Tip
Say these pairs: want/pant, wash/cash, war/car. Feel how W rounds your lips first. For a related pattern, see our post on the A sound after W before L.