Onsite vs. On-site vs. On Site
“On-site” is widely documented as an adjective/adverb, while Cambridge Business English also records “onsite.” Open “on site” remains an ordinary prepositional phrase, as in materials being on site.
“On-site” is a standard adjective/adverb, and Cambridge Business English also records closed “onsite.” Use open “on site” when “on” functions as an ordinary preposition before the noun “site.”
Key details
Choose the right form
| If you mean / need | Use | Why |
|---|---|---|
| a modifier or adverb meaning at the work/activity location | on-site / onsite | Both closed/hyphenated forms are documented in dictionary sources, with editorial preference varying. |
| ordinary preposition + noun construction | on site | Oxford shows open “on site” in ordinary phrase use. |
Further guidance
Core difference
“On-site” is widely documented as an adjective/adverb, while Cambridge Business English also records “onsite.” Open “on site” remains an ordinary prepositional phrase, as in materials being on site.
Fast Test
Choose by meaning, grammatical function, and documented regional convention rather than treating every visible variant as an error.
Variant Boundary
Hyphenated “on-site” and closed “onsite” are documented forms; open “on site” is structurally different when “site” is an ordinary noun after the preposition.
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.
- ON-SITE — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Hyphenated adjective/adverb “on-site”
- ONSITE — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · Closed workplace adjective/adverb “onsite” in Business English
- site — Oxford Advanced Learner’s Dictionary (opens in a new tab)Oxford Advanced Learner’s Dictionary · Open prepositional phrase “on site” after the noun “site”