Millimeter or millimetre?
In American English write millimeter; in British and Commonwealth English, millimetre. millimeter is a noun meaning “US spelling of millimetre”; millimetre is a noun meaning “An SI/MKS unit of measure, the length of ¹⁄₁₀₀₀ of a metre. Symbol: mm”. In written English (wordfreq, 2021 data) millimeter is about 3.4 times as common as millimetre.
What is the difference between millimeter and millimetre?
| millimeter | millimetre | |
|---|---|---|
| Part of speech | noun | noun |
| Meaning | USUS spelling of millimetre | An SI/MKS unit of measure, the length of ¹⁄₁₀₀₀ of a metre. Symbol: mm |
| Example | none recorded | Holonyms: centimetre < decimetre < metre < kilometre < megametre < gigametre < terametre < petametre |
| Forms | millimeters | millimetres millimètres |
| Pronunciation | /ˈmɪləˌmitɚ/ [ˈmɪləˌmiɾɚ] | not recorded |
| Region | US | no label |
| In writing | 1.3 times per million words | about once in every 3 million words |
Sources: millimeter and millimetre in the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Every current meaning of millimeter and millimetre
millimeter
- 1
USUS spelling of millimetre
millimetre
- 1
An SI/MKS unit of measure, the length of ¹⁄₁₀₀₀ of a metre. Symbol: mm
Holonyms: centimetre < decimetre < metre < kilometre < megametre < gigametre < terametre < petametre
Source: the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); obsolete, archaic, dialect and rare senses left out.
Which is more common, millimeter or millimetre?
millimeter appears 1.3 times per million words; millimetre about once in every 3 million words.
millimeter 1.3 times per million wordsmillimetre about once in every 3 million words
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How many people search millimeter vs millimetre?
“millimeter vs millimetre” is searched about 10 times a month on Google (Bing reports no separate figure) in the United States. Google counts close variants of a query together (“millimetre vs millimeter”, “millimeter or millimetre”).
Sources: Google Ads keyword data through DataForSEO and Microsoft Advertising keyword data through DataForSEO, the average month from September 2025 to August 2026.