I often see "replace with" and "replace by" used interchangeably, but this doesn't sound right to me:

I replaced that component by this one.

I would use "with" in such a sentence. "By" only seems reasonable in passive, although "with" sounds like it would there work too:

That component was replaced by this one.
That component was replaced with this one.

In my native language, the equivalent of "replace by" can only be used in passive, and even then it's a bit weird unless a person is the object replacing something – perhaps this affects my judgment?

Web searches haven't come up with anything conclusive; the results are contradictory and speculative at best.

Are "replace with" and "replace by" interchangeable in active context? What about passive? Are there stylistic reasons to prefer one over the other?

  • Related: Substitute X for Y. – choster Jul 28 '14 at 15:25
  • Regarding the active voice, I've noticed that mathematics academia uses "replace A by B" almost exclusively, although I'm not sure why. In common conversation, I notice "replace A with B" almost exclusively. Regarding the passive, it seems that almost everyone uses "A was replaced by B." – Jeff Grimes Apr 27 '15 at 16:13

OP is right to suspect active/passive has a bearing on preferred usage. From Google Books...

1: Active voice favours with...
The company replaced workers by machines - 3 results
The company replaced workers with machines - 405 results

2: Passive voice favours by...
Workers were replaced by machines - 280 results
Workers were replaced with machines - 5 results

To be honest, I can't say I think there's anything wrong with the "less favoured" versions above, and it would be ridiculous to suggest there's any semantic difference. But note that whereas...

Tom replaced Dick by Harry
Tom replaced Dick with Harry

...are both equivalent (manager Tom took Dick off the team, and put Harry in instead), if we want to put that into the "passive" voice, we can only recast it as...

Dick was replaced by Tom with Harry
...or (more likely, imho)...
Dick was replaced with Harry by Tom

That's to say, if the "passive" form actually specifies the "agent", we have to use by for that agent. So we can only use with for the "replacement" in such (slightly contrived) constructions.

  • 1
    With the last sentence in mind. The sentence "Workers were replaced by machines" could be mis-interpreted that the machines are the agent that replaced the workers? In this case I would prefer the "with" version to avoid confusion - (at least in a far future this might happen) – Daniel Alder Mar 1 '18 at 14:39
  • @Daniel Alder: I think that would be a somewhat perverse interpretation, so I can't see it would justify hoping that the current preference for by in my example pair #2 should disappear at some far future time. I don't know why the preposition preference should be reversed between active and passive contexts, but it's so strong it seems unlikely to change. – FumbleFingers Mar 1 '18 at 16:00
  • 2
    I was talking about a future where machines make decisions like "lets replace our workers". That way, the workers really get replaced BY machines (and probably also WITH machines), whereas the BY is the agent and the WITH the object which is used instead of the workers – Daniel Alder Mar 2 '18 at 19:53

In many, (maybe even most?), contexts, replace with and replace by will be interchangeable.

I don't think this has to do with active or passive voice.

Two types of objects can follow replace with and replace by -- the means / method of replacement or the new content. I would say there is a bias for using by to indicate means and with to indicate the substituted content, but I don't think this is an absolute rule:

an example of the former:

Replace numbers by doubling them.

An example of the latter:

Replace all words with codes.

  • "Replacing by" can also denote that the thing being replaced is also displaced. For example, I can imagine being replaced by a computer, but I'm not sure what it would mean for me to be replaced with a computer. – Niel de Beaudrap Feb 11 '14 at 17:33
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    @NieldeBeaudrap replacing me with a computer and me being replaced by a computer both sound find to me. E.g., I am so angry that I was replaced by a computer = I am so angry that I was replaced with a computer. Replaced by is significantly more frequent but replaced with is growing (books.google.com/ngrams/…) – virmaior Feb 11 '14 at 17:44

I have a simple rule. If we are focusing on the replacement function of a subject, we would say: A is replaced by B If we are focusing on the replacement of the subject itself, we would say: A is replaced with B.

Let me know if this works. =)

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    What is the derivation of this rule? – Chenmunka Jan 30 '15 at 18:37

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