is contained of (contains)

Quick answer

Don't use "is contained of." Say either the active verb contains (The box contains books.) or the passive with in (The books are contained in the box.).

"The box contains the books." - correct (active).
"The books are contained in the box." - correct (passive + in).
"The box is contained of books." - incorrect; the preposition of is wrong here.

Core explanation

Contain is a transitive verb: it takes a direct object. Active: container contains content. Passive: content is contained in container. Combining a passive form with of ("is contained of") mixes the wrong preposition and is ungrammatical.

Active pattern: [Container] contains [items].
Passive pattern: [Items] are contained in [container].
Avoid: be contained of + items.

Real usage and tone: when to use contains vs is contained in

Use contains for clear, concise statements-reports, labels, captions. Use is/are contained in when the emphasis falls on the item or its location-storage notes, legal wording, data descriptions. In casual speech, has or holds often sounds more natural.

Concise/neutral: The folder contains the signed forms.
Emphasis on location: The signed forms are contained in the folder.
Casual: The bag holds my headphones and charger.

Examples: common wrong → right pairs (copy these)

Six frequent mistakes and correct rewrites. Read the pattern, then swap your own nouns.

Wrong: The folder is contained of old invoices.
Right: The folder contains old invoices.
Wrong: The book is contained of interesting stories.
Right: The book contains interesting stories.
Wrong: The package is contained of fragile parts.
Right: The package contains fragile parts.
Wrong: The spreadsheet is contained of financial forecasts.
Right: The spreadsheet contains the financial forecasts.
Wrong: The syllabus is contained of weekly topics.
Right: The syllabus contains weekly topics.
Wrong: The list is contained of volunteers' names.
Right: The list contains the volunteers' names.

How a writing assistant helps

A good assistant flags repeated preposition errors, suggests context-appropriate rewrites, and explains the reason so you learn the pattern rather than patch one sentence. Use a checker to catch these errors across emails, reports, and essays.

Work examples (email, report, doc) - ready rewrites

Email: The archive contains last year's invoices; see the "2024" folder on the server.
Report: The appendix contains the raw survey data used in Chapter 3.
Documentation: The configuration file contains the connection string under [database].

School examples (essay, syllabus, lab) - ready rewrites

Essay: The chapter contains three historical case studies relevant to the thesis.
Syllabus: The course packet contains all required readings for the semester.
Lab report: The calibration results are contained in Table 2.

Casual examples (texts, posts, messages) - natural rewrites

Text: My cooler has sandwiches and drinks-help yourself.
Post: The box under the table contains the party decorations.
Message: The tote holds my laptop and charger.

Try your own sentence

Test the whole sentence instead of isolating the phrase. Context clarifies whether the container or the content should be the subject.

Rewrite help: templates and quick fixes

Pick the template that matches your tone: active, passive/location, or casual.

Active template: [Container] contains [items].
Passive/location template: [Items] are contained in [container].
Casual template: [Container] has/holds [items] or Inside the [container] are [items].

Fix 1: "The box is contained of books." → "The box contains books."
Fix 2: "The files are contained of the folder." → "The files are contained in the folder." / "The folder contains the files."
Fix 3: "My tote is contained of lunch and notes." → "My tote has lunch and notes." / "The tote contains my lunch and notes."

Memory trick and formatting checklist (hyphenation & spacing)

Memory trick: contain ≈ hold. If it sounds like "is held of," it's wrong-think "the container contains the content."

Formatting note: this is not a hyphenation issue. Still, check for stray spaces or broken lines that hide errors.

If the container is the subject → use contains.
If the item is the subject and location matters → use is/are contained in.
Casual voice → use has or holds.
Proofreading checklist: search your draft for "is contained of" → apply a template above → read the sentence aloud to confirm emphasis.

Similar mistakes and quick fixes

These close cousins cause similar confusion. Choose the form that matches meaning and idiom.

"Comprise" vs "is comprised of": prefer comprises or is composed of.
"Consist of" is correct when listing parts that make up a whole.
Remember: contained + in = correct passive; contained + of = incorrect.

Wrong: The committee is comprised of five members.
Right: The committee comprises five members. / The committee is composed of five members.
Wrong: The file is contained of confidential notes.
Right: The file contains confidential notes. / The notes are contained in the file.
Wrong: The team is consisted of veterans.
Right: The team consists of veterans.

FAQ

Can I say "is contained of"?

No. Use contains (active) or is/are contained in (passive + in). "Is contained of" is nonstandard.

When should I use contains vs is contained in?

Use contains when the container is the subject. Use is/are contained in when you emphasize the item or its location.

Is "contains of" ever correct?

No. Contains does not pair with of. Use contains [object] or [object] is contained in [container].

How do I rewrite "The box is contained of books" quickly?

Either: "The box contains books." (active) or: "The books are contained in the box." (passive/location).

Which preposition goes with contained in the passive voice?

Use in: "[Items] are contained in [container]." Avoid of in that structure.

Want a quick check?

If you're unsure, paste the sentence into a grammar tool to flag "is contained of" and suggest "contains" or "is contained in." A quick scan saves time and helps the pattern stick.

Tip: Run that check once across a draft to catch multiple instances at once.