iff vs its, What's the Difference?

Which to use

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

#45,443
“iff” frequency rank: #75
“its” frequency rank: 45518
confusion score

Side-by-Side Comparison

Feature	iff	its
Definition	Abbreviation of if and only if.	Belonging to it.

Where the spellings diverge

Shared letters are muted; the letters that actually set iff and its apart are highlighted. They share 1 letter in sequence, which is exactly why the eye skips the difference.

3 ch

iff

3 ch

its

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: iff is /ɪf ən(d)ˈəʊn.li ɪf/ while its is /ɪts/. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (conjunction vs determiner), which is usually the fastest check. Our composite confusion score for this pair is 45518, 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/. its is at rank #75, tagged as adet, pronounced /ɪts/.

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 45518, this pair ranks #220,545 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of iff vs its

Shared letters: i. Private to "iff": f. Private to "its": st.

"iff" · 3 letters · shape VCC · "its" · 3 letters · shape VCC

Frequency comparison

iff#45,443

its#75

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "iff" and "its" be used interchangeably?

No - they are not even the same part of speech. "iff" is a conjunction and "its" a determiner, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "iff" or "its"?

"its" is the more common of the two: it sits at frequency rank #75 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.

Remembering iff vs its

The fastest way to pick the right one every time.

Check the role first: if you need a conjunction, it's “iff”; for a determiner, it's “its”.
See each word in full, definition, IPA, etymology and its other confusables. Full “iff” entry
Browse more pairs most likely to be confused. Most confusable