kilometervskilometreWhat's the difference?

Which to use

“kilometer” and “kilometre” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#22,717
“kilometer” frequency rank
#22,131
“kilometre” frequency rank
44848
confusion score

Side-by-Side Comparison

Feature kilometer kilometre
Definition US spelling of kilometre. An SI unit of length equal to 10³ metres. Symbol: km

Where the spellings diverge

Shared letters are muted; the letters that actually set kilometer and kilometre apart are highlighted. They share 8 letters in sequence, which is exactly why the eye skips the difference.

9 ch
kilometer
9 ch
kilometre

Spelling & Dictionary Insight

This is the hard kind. kilometer and kilometre are pronounced identically (/kɪˈlɒmɪtə/) and both work as anoun. Neither the ear nor the grammar will rescue you; only the meaning does, so the glosses below are the whole decision. They differ only by swapping two adjacent letters (er ↔ re) - a transposition the eye reads straight past. Our composite confusion score for this pair is 44848, derived from the frequency rank of both members and their visual similarity.

kilometer is recorded at frequency rank #22,717, classified as anoun, pronounced /kɪˈlɒmɪtə/. kilometre is at rank #22,131, tagged as anoun, pronounced /kɪˈlɒmɪtə/.

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 44848, this pair ranks #226,759 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of kilometer vs kilometre

Shared letters: eiklmort. Private to "kilometer": -. Private to "kilometre": -.

"kilometer" · 9 letters · shape CVCVCVCVC  ·  "kilometre" · 9 letters · shape CVCVCVCCV

Known mistypes of this pair

  • kilometeriklometer · killometer · kilmoeter · kiloemter · kilomeetr · kilometerr · kilometter · kilommeter
  • kilometreiklometre · killometre · kilmoetre · kiloemtre · kilomerte · kilometrre · kilomettre · kilommetre

Frequency comparison

kilometer#22,717
kilometre#22,131

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "kilometer" and "kilometre" be used interchangeably?
No. They are pronounced the same (/kɪˈlɒmɪtə/), which is exactly why they get swapped in writing, but the dictionary meanings above are different, and pronunciation is no guide here.
Which is more common, "kilometer" or "kilometre"?
"kilometre" is the more common of the two: it sits at frequency rank #22,131 in our English list, against #22,717 for "kilometer". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Remembering kilometer vs kilometre

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 “kilometer” entry
  • Browse more pairs most likely to be confused. Most confusable

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list