sei vs seis, What's the Difference?

Which to use

“sei” and “seis” are a confusable Spanish pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#48,072
“sei” frequency rank: #596
“seis” frequency rank: 48668
confusion score

Side-by-Side Comparison

Feature	sei	seis
Definition	Seis.	Cinco y uno.

Where the spellings diverge

Shared letters are muted; the letters that actually set sei and seis apart are highlighted. They share 3 letters in sequence, which is exactly why the eye skips the difference.

3 ch

sei

4 ch

seis

Spelling & Dictionary Insight

A purely visual mix-up. sei (/s̺ej/) and seis ([ˈsejs]) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they differ by 1 extra letter(s) - “sei” sits inside “seis”. Our composite confusion score for this pair is 48668, 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/. seis is at rank #596, tagged as anum, pronounced [ˈsejs].

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 48668, this pair ranks #113,168 of 323,831 scored Spanish confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of sei vs seis

Shared letters: eis. Private to "sei": -. Private to "seis": -.

"sei" · 3 letters · shape CVV · "seis" · 4 letters · shape CVVC

Known mistypes of this pair

seis ← ceis · esis · seiss · sesi · sies · sseis

Frequency comparison

sei#48,072

seis#596

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

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

No. They are said differently (/s̺ej/ versus [ˈsejs]) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.

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

"seis" is the more common of the two: it sits at frequency rank #596 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.

Remembering sei vs seis

The fastest way to pick the right one every time.

Read both glosses above and match the meaning you intend, only context separates this pair.
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