sei vs soi, What's the Difference?

Which to use

“sei” is a num and “soi” is a verb - they look or sound alike but fill different roles in a sentence.

#48,072
“sei” frequency rank: #38,396
“soi” frequency rank: 86468
confusion score

Side-by-Side Comparison

Feature	sei	soi
Definition	Seis.	Segunda persona singular informal en el voseo chileno (vos) del presente de indicativo del verbo ser.

Where the spellings diverge

Shared letters are muted; the letters that actually set sei and soi apart are highlighted. They share 2 letters in sequence, which is exactly why the eye skips the difference.

3 ch

sei

3 ch

soi

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: sei is /s̺ej/ while soi is [ˈsoj]. Spoken aloud the problem disappears. In writing it persists, because they differ by a single letter - e in “sei” becomes o in “soi”, and the parts of speech differ too (num vs verb), which is usually the fastest check. Our composite confusion score for this pair is 86468, derived from the frequency rank of both members and their visual similarity.

sei is recorded at frequency rank #48,072, classified as anum, pronounced /s̺ej/. soi is at rank #38,396, tagged as averb, pronounced [ˈsoj].

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 86468, this pair ranks #5,267 of 323,831 scored Spanish confusable pairs - among the most confusable pairs.

Orthographic DNA of sei vs soi

Shared letters: is. Private to "sei": e. Private to "soi": o.

"sei" · 3 letters · shape CVV · "soi" · 3 letters · shape CVV

Frequency comparison

sei#48,072

soi#38,396

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "sei" and "soi" be used interchangeably?

No - they are not even the same part of speech. "sei" is a num and "soi" a verb, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "sei" or "soi"?

"soi" is the more common of the two: it sits at frequency rank #38,396 in our Spanish list, against #48,072 for "sei". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Remembering sei vs soi

The fastest way to pick the right one every time.

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