In the sentence, "Immigration increased by 28%", would the "by" be correct or could the sentence read, "Immigration increased 28%"?

  • Should be a difference, but I don't see it. Apr 1, 2022 at 14:10
  • 1
    Does this answer your question? Increase or increase by? Also increase 10% or increase by 10%? Apr 1, 2022 at 15:22
  • Although the two instances noted by Edwin Ashworth are indeed duplicates of the basic question here, both are closed for lack of research, meaning that anyone who might have a clear and persuasive answer (not me) would have nowhere to put it if this question were closed and no other version of the question were reopened. For that reason—and because it appears to be a question of perennial interest to site visitors—I'm voting to keep this question open.
    – Sven Yargs
    Apr 1, 2022 at 23:23
  • Preposition deletion hereabouts is idiosyncratic: 'Increased 20%' but ??'increased a fifth'. It seems fairly random, though I'd say retention of 'by' is more common in the UK than in the US. But basic research is needed (the reason earlier dupes were closed). In the final analysis, what is acceptable in certain related cases is found by checking corpora / Google ngrams. Here, either is of course acceptable (though the Google ngram I checked indicates a significant return to favour of the undeleted form: 7 : 1). Apr 2, 2022 at 14:17

1 Answer 1


In general use, these appear to have the same meaning. All I would say is that I would include the word 'by', otherwise it leaves the phrase sounding a bit stark and unnatural. Brevity is good, but it can be overdone!

I know this isn't part of the question, but I think it's worth mentioning:

There is an important difference between 'percentage' and 'percentage points'. For example, in the UK, when VAT increased from 15% to 20%, some reports said it had increased by 5%. What they should have said is "5 percentage points". The actual increase, as a percentage of the original rate, was 33⅓% (5 is one third of 15).

  • Most people don't treat these things using pedantic mathematics. When talking about a change to something that's reported as a percentage, it's almost always understood that you're talking about the absolute change, not the ratio between the old and new percentages.
    – Barmar
    Apr 1, 2022 at 22:47
  • This is also probably why the financial industry uses the phrase "basis points" instead of "percentage".
    – Barmar
    Apr 1, 2022 at 22:48

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