The spelling of the phrase "had on carpet" is straightforward, with each word representing its respective sounds. "Had" is pronounced as /hæd/ with a short "a" sound followed by a voiced "d" sound. "On" is pronounced as /ɑn/ with a nasal "a" sound followed by a voiceless "n" sound. Lastly, "carpet" is pronounced as /kɑrpɪt/ with a nasal "a" sound, followed by a voiced "r" sound, and ending with a voiceless "t" sound. Together, the phrase is pronounced as /hæd ɑn kɑrpɪt/.