Commonly confused

Phase in vs Phase out

Phase in” and “Phase out” look alike but pull in different directions. Here is what each one means, with examples — and the difference that learners most often miss.

The key difference

Phase in means introduce something gradually in stages. Phase out means discontinue gradually.

phase in

  1. 1

    Introduce something gradually in stages

    They'll phase in the new system.

Full meaning of phase in

phase out

  1. 1

    Discontinue gradually

    They phased out the old model last year.

Full meaning of phase out

Stop mixing them up

Sink In turns confusable pairs like this into quick contrast drills, so the right particle becomes automatic.