Caliber vs. Calibre
“Caliber” and “calibre” are regional spellings of the same noun. Cambridge marks caliber US and calibre UK across the quality and measurement senses.
Use “caliber” in US English and “calibre” in UK English unless your house style specifies another convention.
Key details
Choose the right form
| Meaning / situation | Construction | Decision |
|---|---|---|
| US English spelling | caliber | use in US-oriented prose |
| UK English spelling | calibre | use in UK-oriented prose |
Quick tests
Regional-style test
Is the document following US spelling conventions?
If yes: Use “caliber.”
If no: Use “calibre” when UK spelling is required or preferred.
Caveat: This is a regional spelling distinction, not a difference in meaning; follow house style consistently.
Examples
The company is looking for candidates of a high caliber.
“Caliber” is the US spelling.
The laboratory recruited researchers of a high calibre.
“Calibre” is the UK spelling.
Do not mix “caliber” and “calibre” randomly within the same house style.
Consistency is the practical editing rule when both forms are standard.
Further guidance
Core difference
Cambridge identifies “caliber” as the US form and “calibre” as the UK form.
Fast Test
Match the spelling to the regional or house style required by the document, then keep that choice consistent.
Variant Boundary
The regional spelling distinction applies across the cited noun senses; it is not a meaning difference.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Caliber — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Caliber identified as the US form corresponding to UK calibre
- Calibre — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Calibre identified as the UK form corresponding to US caliber