fast vs Fax, What's the Difference?

Which to use

“fast” is an adverb and “Fax” is a noun - they look or sound alike but fill different roles in a sentence.

#243
“fast” frequency rank: #12,705
“Fax” frequency rank: 12948
confusion score

Side-by-Side Comparison

Feature	fast	Fax
Definition	nicht ganz	per Telefonleitung übermitteltes Dokument, Schriftstück, Foto oder Zeichnung

Where the eye mixes fast and Fax

Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.

4 ch

fast

3 ch

Fax

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: fast is [fast] while Fax is [faks]. 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 (adverb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 12948, derived from the frequency rank of both members and their visual similarity.

fast is recorded at frequency rank #243, classified as anadv, pronounced [fast]. Fax is at rank #12,705, tagged as anoun, pronounced [faks].

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 12948, this pair ranks #1,961,054 of 2,006,359 scored German confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of fast vs Fax

Shared letters: af. Private to "fast": st. Private to "Fax": x.

"fast" · 4 letters · shape CVCC · "Fax" · 3 letters · shape CVC

Known mistypes of this pair

fast ← afst · fastt · fats · ffast · fsat

Frequently Asked Questions

Can "fast" and "Fax" be used interchangeably?

No - they are not even the same part of speech. "fast" is an adverb and "Fax" a noun, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "fast" or "Fax"?

"fast" is the more common of the two: it sits at frequency rank #243 in our German list, against #12,705 for "Fax". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

You've compared "fast" and "Fax". Here's where to go from here.

Full dictionary entry for "fast" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "Fax" - compare definitions side by side with the headword page. Word entry
This pair ranks #1,961,054 of 2,006,359 scored German confusable pairs in this corpus vintage. Corpus statistics
"fast" and "Fax" also get mixed up with nearby pairs, the highest-scored neighbour is "Fack vs Fax". Nearby pair
Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

PlainSpell is a reference corpus, not spelling advice. Verify unusual forms in context.