The OALD gives two pronunciations for have to: /ˈhæf tə/ and /ˈhæv tə/. It also gives two pronunciations for has to (/ˈhæz tə/, /ˈhæs tə/) and had to (/ˈhæd tə/, /ˈhæt tə/).

When is have to pronounced /ˈhæf tə/? Does the pronunciation change basing on the following word, as it happens with the, or are there other rules?

  • There's a fuller exploration on this ELU question. Related variations in pronunciation also occur with other verbs, including used to when it means was accustomed to, and was supposed to when it means ought to have. Commented Jun 8, 2013 at 21:01

2 Answers 2


It is pronounced /ˈhæf tə/ when it acts as a semi-modal, equivalent to must, AND the two words fall together. In all other circumstances it is pronounced as /ˈhæv tə/.

ADD: Actually, the to in /ˈhæv tə/ will in most cases be pronounced /tᵿ/, but that's a very minor point.

 I /ˈhæf tə/ tell you the truth: I have no idea what you're talking about.
 I /ˈhæv/, /tə/ tell you the truth, no idea what you're talking about.
 We /ˈhæv/ /tə/ the left, the Colosseum; /tə/ the right, the Arch of Constantine.
 We /ˈhæv/ /tə/ that end instituted a new policy.
 I /ˈhæf tə/ go to Ottawa tomorrow.
 ?I /ˈhæv/, /tə/ my dismay, to go to Ottawa tomorrow.

You're very unlikely to hear the last one. It's not formally "incorrect", but only a very literate speaker or writer, familiar with similar uses of full modals, would think that have to might be be deployed with an adverbial between the auxiliary and the lexical verb; and only a speaker or writer with a tin ear would allow himself to do so.

  • What is the pronunciation of have to in "You simply have to get a new job"? I ask because in two if your examples, to is part of a parenthetical.
    – apaderno
    Commented Jun 8, 2013 at 17:39
  • @kiamlaluno With /f/ = "You simply must get a new job." Almost any prepositional phrase in that position is going to be adjunctive, and thus virtually by definition 'parenthetical'. I've added a couple of exx that are less emphatically bracketed. Commented Jun 8, 2013 at 18:15
  • To be clearer: I am referring to what said from the OALD about have to (modal verb). Are there any cases where the verb is modal, but it is not semi-modal? I ask because you say, "It is pronounced /ˈhæf tə/ when it acts as a semi-modal, equivalent to must."
    – apaderno
    Commented Jun 10, 2013 at 9:20
  • When I said parenthetical, I should have said parenthesis. Clearly, I would not pronounce have, to as /ˈhæf tə/ because the comma, and "I have no idea" is not using have to as modal verb.
    – apaderno
    Commented Jun 10, 2013 at 9:23
  • @Kiamlaluno It's called a "semi-modal" because unlike the full modals it a) takes a to-infinitive, not a bare infinitive, and b)it has non-finite forms and can be used modally in constructions using those forms: I will have to go, I have had to go, I am having to go. Note that the deviant pronunciation occurs with the infinitive: I will hafta go. Commented Jun 10, 2013 at 11:09

StoneyB has explained well the contexts in which hafta is used, but I'm going to shed some light on why 'have to' is pronounced hafta.

I have explained it in some other answers as well, such as this one [Why does the B change to a P when -tion is added to 'absorb'].

Voicing assimilation is what happened here. In voicing assimilation, one of the two adjacent sounds changes its voicing. It's rather difficult to pronounce two adjacent obstruents that disagree in voicing. The /v/ at the end of 'have' is voiced while the /t/ at the beginning of 'to' is voiceless, so the /v/ anticipates the /t/ and changes it's voicing (i.e. from voiced to voiceless) and becomes /f/ because /f/ is the voiceless counterpart of /v/.

  • /hæv tə/ → /hæf tə/ (hafta)

The same thing happens to has to:

  • /hæz tə/ → /hæs tə/ -- the /z/ changes its voicing and becomes /s/

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