iffvsitWhich spelling fits?

Quick tell: iff is a conjunction, it is a pronoun, so they fill different roles in a sentence.

Which to use

“iff” is a conjunction and “it” is a pronoun - they look or sound alike but fill different roles in a sentence.

#45,443
“iff” frequency rank
#12
“it” frequency rank
45455
confusion score

Side-by-Side Comparison

Feature iff it
Definition Abbreviation of if and only if. The third-person singular neuter personal pronoun used to refer to an inanimate object, abstract entity, or non-human living thing.

Where the eye mixes iff and it

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence. iff runs 3 letters (VCC) against it's 2 (VC) - the length gap alone is often enough to separate them once you know to check it.

3 ch
iff
2 ch
it

Why the eye confuses iff with it

These two trip readers on the page rather than in the ear: iff is /ɪf ən(d)ˈəʊn.li ɪf/ while it is /ɪt/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (conjunction vs pronoun), which is usually the fastest check. Our composite confusion score for this pair is 45455, derived from the frequency rank of both members and their visual similarity.

iff is recorded at frequency rank #45,443, classified as aconj, pronounced /ɪf ən(d)ˈəʊn.li ɪf/. it is at rank #12, tagged as apron, pronounced /ɪt/.

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 45455, this pair ranks #221,125 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of iff vs it

Shared letters: i. Private to "iff": f. Private to "it": t.

"iff" · 3 letters · shape VCC  ·  "it" · 2 letters · shape VC

Frequently Asked Questions

Do "iff" and "it" mean the same thing in a sentence?
No - they are not even the same part of speech. "iff" is a conjunction and "it" a pronoun, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "iff" or "it"?
"it" is the more common of the two: it sits at frequency rank #12 in our English list, against #45,443 for "iff". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

  • Full dictionary entry for "iff" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "it" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #221,125 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "iff" and "it" also get mixed up with nearby pairs, the highest-scored neighbour is "iff vs ith". Nearby pair

Confusion rank #221,125 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

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

Source: FrequencyWords open word-frequency list