How To Pronounce How's

In British English, how's is pronounced /haʊz/. The narrow phonetic transcription is [haʊz]. In American English, it is pronounced /haʊz/.

How's has one syllable. British and American speakers say it the same way.

Slashes / / show the phonemic transcription, the sounds that change meaning. Square brackets [ ] show the phonetic transcription, with the finer detail of how the sounds are actually made.