Approx./approx. are documented shortened forms of approximate/approximately. This is a style-and-abbreviation question rather than a universal punctuation law.
ReviewedEvidence1 sourceSectionWriting & Style
Quick answer
“Approx.” is a standard written abbreviation for “approximately”; “approx” also appears in Business English. Whether to keep the period can depend on house style.
Key details
Core IssueApprox. is a documented written abbreviation for “approximately”; Cambridge Business English also records approx and approx. for “approximate.”
Phrase Roleabbreviation mechanics
Registergeneral and business writing
Important caveats
Style Boundary
Follow the relevant house style and keep the abbreviation consistent; spell the word out where compact notation is unnecessary.
Variant Boundary
Cambridge Business English also records “approx” and “approx.” for “approximate,” so a final period is not universal across all style systems.
Further guidance
Meaning
Cambridge records “approx.” as a written abbreviation for “approximately.”
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.
Dept/dept. abbreviates department. Cambridge shows periodless and period-ending forms across its dictionary varieties, so the useful rule is to follow the relevant regional or organizational style consistently.
Est. is a documented abbreviation with more than one common expansion. The page distinguishes meaning, capitalization, and punctuation rather than presenting one context-free rule.
“No.” is a conventional abbreviation for “number” in Chicago-style contexts. The guide keeps it distinct from the number sign and from shortened forms such as num. or n., which may carry other meanings.
