Is there a difference in meaning between "fill {something} in" and “fill {something} out” in American English?

Question

Is there a subtle or significant difference in meaning between the following?

1. fill something in

2. fill something out

In my humble opinion, the two expressions are interchangeable and both mean to complete something, usually it's a form or an official document by filling in the blank spaces or filling it out i.e. become full.

However, is it true in some American English dialects, fill in means to supply information whilst fill something out means to complete something in its entirety?

This piece of information was imparted to me by a very competent American English speaker.

I am referring to an aspectual difference when out is used in conjunction with the verb.

I disagreed, based on instinct (common sense?), I sustain that there is no difference in meaning between the two. Oxford Living Dictionaries doesn't mention this subtle difference in meaning but I'm not an American English native speaker, maybe the user is onto something?

Answer 1

The distinction between fill out and fill in is rather ambiguous.

Generally speaking, in the US, "fill out" means to "complete" the form -- supply all applicable information. "Fill in" means to put specific data in a specific place. Eg, "fill in your Social Security" number.

But, as I said, this distinction is not especially strong, and the context should be taken into account to hopefully either confirm or contradict this general assumption.

Answer 2

Yes, they both definitely mean that but one is American, the other one is British, however both are in use in AmE per my experience, as to the different aspect:

Fill something out per ODO:

North American

1 Add information to complete an official form or document.
‘he filled out the requisite forms’

Fill something in per ODO:

1.2 British Add information to complete something, typically a form or other official document.

‘he filled in all the forms’

And I agree with the AmE speaker who said they seem different in aspect. And I believe that difference in aspect comes from the adverbs in and out that are part of the two phrasal verbs.

fill + in

From Merriam-Websters in:

1 c : to or at an appropriate place

fill + out

From Merriam-Websters out:

3 b : to completion or satisfaction

3 c : to the full or a great extent or degree

Please also note comment below from @tchrist, where he points out the very good point that both AmE and BrE have their own idiomatic uses. In my answer I strictly intended to point out the difference between AmE and BrE in meaning "to complete a form", and the difference between the adverbs.

Answer 3

In British English, we would understand both "fill it out" and "fill it in" to mean the same thing with regard to e.g. a form – though I believe "fill it in" would be more commonly used.

I think "fill this out" would sound more awkward to British ears, but "fill that out" less so, because the implied distance in 'that' matches the tone of 'out'.

However, if it's with regard to a person, only "fill in" is used – e.g. "Can you fill me in on the meeting I missed?", or "Please fill Tom in on the details". We would not say "Please fill me out".

Answer 4

These are often used interchangeably, but they have slightly different connotations. The difference is:

"Fill this in" is definitely singular, while

"Fill this out" typically refers to a plurality

This is obvious if you consider the word "in". In order to "fill something in", there must be some thing (singular) to put a response inside.

As an example, "in" would be preferred for this strictly singular case:

"Fill in the box" (There's a single box)

This is difficult when referring to a form, because a form is a collection of boxes to be filled out. Thus it can be:

"Fill in a form" (referring to the singular form)

or

"Fill out a form" (referring to the collection of elements that make up the form)

As a final example:

"Fill out these forms"

would be less awkward than

"Fill in these forms"

However, they're both technically correct, since the collection of forms could be interpreted as a single item.

Answer 5

The following extract may help understand the usage of fill in vs fill out also from the BrE perspective vs the AmE one:

Of the two, fill in seems more logical. If you’ve got a form, it has blank spaces which you have to fill by putting information in those spaces. Fill on its own wouldn’t work, not in reference to the form as a whole. You fill the spaces, sure, but filling a form would feel like you were covering every last millimetre of the form with ink. And that’s probably not what you’re supposed to do.

So what about fill out then? First of all, it seems like it’s used more often in American English than British English. Searching the Corpus of Contemporary American EnglishCorpus of Contemporary American English provides more results for fill out a form than fill in a form. This may be a result of the influence of German-speaking immigrants on American English, as the German phrase ausfüllen can be directly translated to fill out. I’ve tried checking the British National Corpus, but it’s not working as of time of writing. Anecdotally though, it seems fill in is more common in British English. Here in Ireland we tend to use both, as we’re exposed to both British and American English quite often.

Thinking now actually, even though fill in might seem more logical, fill out also seems kind of logical. It makes sense in terms of filling out a whole form, as the out conveys a sense of expansiveness, probably related to the concept of outside that goes along with it.

For a lot of people, I think it makes sense to say fill out a form, but perhaps fill in a specific section of a form. That’s probably why, when we want someone to give us information, we tell them to fill us in. We want them to put this specific information in our mind, like when we fill in a particular section of a form. Fill us out just wouldn’t make sense in that context.

(englishlanguagethoughts.com)