sei vs sería, What's the Difference?

Which to use

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

#48,072
“sei” frequency rank: #336
“sería” frequency rank: 48408
confusion score

Side-by-Side Comparison

Feature	sei	sería
Definition	Seis.	Primera persona del singular (yo) del condicional de ser.

Where the eye mixes sei and sería

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence. sei runs 3 letters (CVV) against sería's 5 (CVCVV) - the length gap alone is often enough to separate them once you know to check it.

3 ch

sei

5 ch

sería

Why the eye confuses sei with sería

These two trip readers on the page rather than in the ear: sei is /s̺ej/ while sería is [seˈɾia]. Spoken aloud the problem disappears. In writing it persists, because they differ by 2 letter(s) in length, and the parts of speech differ too (num vs verb), which is usually the fastest check. Our composite confusion score for this pair is 48408, 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/. sería is at rank #336, tagged as averb, pronounced [seˈɾia].

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 48408, this pair ranks #114,649 of 323,831 scored Spanish confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of sei vs sería

Shared letters: es. Private to "sei": i. Private to "sería": arí.

"sei" · 3 letters · shape CVV · "sería" · 5 letters · shape CVCVV

Frequently Asked Questions

Do "sei" and "sería" mean the same thing in a sentence?

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

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

"sería" is the more common of the two: it sits at frequency rank #336 in our Spanish list, against #48,072 for "sei". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Useful next steps

Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.

Full dictionary entry for "sei" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "sería" - compare definitions side by side with the headword page. Word entry
This pair ranks #114,649 of 323,831 scored Spanish confusable pairs in this corpus vintage. Corpus statistics
"sei" and "sería" also get mixed up with nearby pairs, the highest-scored neighbour is "sei vs stem". Nearby pair

Confusion rank #114,649 of 323,831 scored Spanish pairs, corpus vintage 2026-09-03, not spelling advice.