A4vsanWhat's the difference?

Quick tell: A4 is a name, an is an article, so they fill different roles in a sentence.

Which to use

“A4” is a name and “an” is an article - they look or sound alike but fill different roles in a sentence.

#18,471
“A4” frequency rank
#30
“an” frequency rank
18501
confusion score

Side-by-Side Comparison

Feature A4 an
Definition A4 class, a class of steam locomotive used on the London and North Eastern Railway. Form of a (all article senses).

Letter map: A4 vs an

Shared letters muted; letters that set A4 and an apart highlighted. Shared run: 1.

2 ch
A4
2 ch
an

Spelling & Dictionary Insight

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: A4 is aname and ananarticle. On the page they differ by a single letter - 4 in “A4” becomes n in “an”. Our composite confusion score for this pair is 18501, derived from the frequency rank of both members and their visual similarity.

A4 is recorded at frequency rank #18,471, classified as aname. an is at rank #30, tagged as anarticle, pronounced /ˈæn/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 18501, this pair ranks #444,473 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of A4 vs an

Shared letters: a. Private to "A4": -. Private to "an": n.

"A4" · 1 letters · shape V  ·  "an" · 2 letters · shape VC

Frequently Asked Questions

Can "A4" and "an" be used interchangeably?
No - they are not even the same part of speech. "A4" is a name and "an" an article, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "A4" or "an"?
"an" is the more common of the two: it sits at frequency rank #30 in our English list, against #18,471 for "A4". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list