The night before a deadline, "check for plagiarism" usually means paste the paper into a checker and hope the number is low. That is the wrong way round. A checker finds text that matches other text. It cannot tell a proper quotation from a copied sentence, and it misses most close paraphrase.
So the check has two steps: an audit you do yourself, against the rules a marker applies, and then a text-matching check, read match by match against the same rules.
This guide gives both, with what the common free and institutional checkers do and do not do, from their own pages on 22 September 2026. EdCitation publishes it and sells a text-matching check, Check plagiarism; its free tools are named at the audit steps they do for you.
What does checking a paper for plagiarism actually involve?
Checking a paper for plagiarism means confirming that every borrowed word and idea is credited the way your style requires, and only then using software to look for borrowed text you missed.
Roig (2015), in the guide to ethical writing hosted by the US Office of Research Integrity, quotes the 1999 federal definition of plagiarism, which turns on using another person's ideas, results or words "without giving appropriate credit". Credit is the test. A copied sentence is proper inside quotation marks with a page number; a sentence with no borrowed words is plagiarism if its idea was someone else's and is not cited.
Software does not apply that test. Foltýnek et al. (2020) open what they describe as the largest test of text-matching systems yet conducted by stating that software "cannot determine plagiarism"; it finds similar text for a person to judge. Turnitin (n.d.-c) says the same of its own product: it does not check for plagiarism, it compares a submission with its database and highlights the matches.
A marker looks at four things: quotations, which must be inside quotation marks, cited, and given a page number where the style requires one, as APA 7 does; paraphrases and summaries, in your own words and your own sentence structure, and cited, because the idea is still the source's; citations and entries, each leading to the other; and the entries themselves, each describing a real source correctly. A checker helps with the first two only, and only partly. The other two are checked by pairing and lookup, not by text-matching: EdCitation's free Verify references takes the whole paper, checks that every citation has an entry and every entry is cited, and looks each entry up in the publisher's record.
How do I audit my paper myself the night before?
Work through the paper once for each of those four, with the sources open beside it. It finds what no checker finds.
- Freeze the draft. Audit after the last edit. Open every source, or the notes that quote them with page numbers.
- Find every quotation. Each passage in a source's words needs quotation marks (or block format, at 40 words or more in APA 7), the citation and the page number. Roig (2015) makes this his second guideline, and notes that some writers believe a citation alone licenses copied text. It does not.
- Put every paraphrase beside its source. Look for the same sentence order and for runs of three or four words that survived. Roig's fourth guideline asks for your own words and your own syntactical structure; what fails it he calls inappropriate paraphrasing: swapping a word or two, reordering, or switching tense or voice. Rewrite from memory with the source closed, or keep the distinctive phrase in quotation marks with a page number. When to paraphrase, quote or summarise shows one passage done both ways.
- Cite every summary and borrowed idea. A summary in your own words still needs a citation, Roig's fifth guideline, and so does an idea you took without its words. When you remember the idea but not where you read it, Find sources searches by the claim the sentence makes; once you have the work, Cite a source builds its entry from the DOI, title or ISBN.
- Match citations to entries both ways. Every citation has an entry with the same name and year; every entry is cited at least once. Uploading the whole paper to EdCitation's Verify references does this pairing for you, free.
- Confirm the reference list. Each entry must describe a real source correctly. An entry copied from another paper's list, or produced by an AI tool, needs looking up. How to check a reference is real gives the method; Verify references does it free, with no account.
- Decide the common-knowledge cases. A widely known fact needs no citation; a finding, an estimate or an interpretation does. Roig's eighth guideline: when in doubt, cite.
- Check anything reused from your own earlier work. The rule is in the section on self-plagiarism below.
Why patchwriting is the thing to look for
Patchwriting is the commonest way an honest writer loses marks, and the one a checker is worst at finding. Pecorari (2003) compared the source-based writing of 17 postgraduate students with the sources and found textual features that could be described as plagiarism, while the students' accounts and the textual analysis pointed to no intention to plagiarise. That is patchwriting: the source's sentences edited one at a time, with the source open.
The American Psychological Association (2022) describes the pattern as a few words changed while the content stays largely the same, and notes that educators use checking software to find it. The next section shows how often that works.
How do I read the matches a plagiarism checker shows?
Read each highlighted match and decide what kind it is. The percentage on its own tells you nothing, and the checkers' makers say so.
Turnitin (n.d.-c) explains that its score is matched words as a share of total words, that correctly quoted and referenced text is still highlighted, that there is no fixed acceptable number, and that a high score does not always mean plagiarism just as a low one does not mean there is none. Foltýnek et al. (2020) recommend that vendors drop the single number altogether, because institutions misuse it as a decision maker.
| What matched | What it usually means | What to do |
|---|---|---|
| A quotation in quotation marks, cited, with a page number | Expected | Nothing, unless it is longer than the point needs |
| A reference list entry | Expected: every paper describes that source the same way | Nothing here; whether the source is real is step 6 |
| A standard phrase: a method name, a title, "the aim of this study was to" | A false positive; Foltýnek et al. (2020) trace most to common phrases | Nothing, unless it runs to a whole sentence |
| A paragraph matching one source phrase after phrase, with a citation | Patchwriting. The citation credits the idea, not the wording | Rewrite from memory, or quote the phrase with a page number |
| A passage matching a source cited nowhere in the paper | Missing credit, whether or not the words were copied | Add the citation, and the entry from Cite a source; put exact words in quotation marks |
| An essay or draft you wrote yourself | Self-plagiarism, or a resubmitted draft | Check the permission rule below |
What a checker finds and what it misses
The best evidence is the test by Foltýnek et al. (2020) of 15 web-based text-matching systems, run by researchers in seven countries with documents in eight languages between November 2018 and November 2019. Each system was scored from 0 to 5 for how much of the known copied text it found. None reached the band the authors called useful, 3.75 or above. Five reached the partially useful band of 2.5 to 3.75: PlagAware, PlagScan, StrikePlagiarism.com, Turnitin and Urkund.
By method: copied and pasted text was found by nearly every system; text disguised with synonyms was found only partly; no system found manually paraphrased text at a satisfactory level, and translated text was missed by all but one, the others matching only the reference list. The systems also flagged text that was not copied at all. Vendors reported improvements afterwards, and the results describe the versions tested. The point stands: the paraphrase you compared with its source in step three is the one no checker can be relied on to find.
What do Turnitin Draft Coach and Grammarly do before submission?
Turnitin Draft Coach runs only where your institution has licensed it and switched it on, and Grammarly's free check reports whether matching text exists without showing it. Both descriptions come from the companies' own pages, read on 22 September 2026.
Turnitin Draft Coach
Draft Coach is an add-on inside Google Docs or Microsoft Word online, not desktop Word, and Turnitin (n.d.-a) says it must be set up by the institution's Turnitin administrator and is "license dependent". An institution enables it in Google Docs or in Word online, not both. Turnitin's pages offer no way for a student to get it without an institution.
Where it is available, it gives three similarity reports for each draft, compared against web pages, papers other students have submitted to Turnitin, and periodicals and journals (Turnitin, n.d.-b). The draft is not added to Turnitin's repository, and the results cannot be shared with an instructor (Turnitin, n.d.-a). Its Citation Check detects MLA and APA and lists a citation with no reference and a reference with no citation; Turnitin's guide says it will not catch a source that has neither, which is the case that matters most. Without it, Check plagiarism below needs no institution.
Grammarly's plagiarism checker
Grammarly's checker page offers a free check that, in its own words, will "tell you whether or not there is any duplicate content", and says its Premium check "highlights passages that require citations" (Grammarly, n.d.-a). The database is given as over 16 billion web pages plus ProQuest's academic papers. Grammarly's support pages add that the checker is not available on a Free account (Grammarly, n.d.-c) and is provided on its paid plans, where it marks matching passages with bars beside the text and suggests citations in MLA, APA and Chicago (Grammarly, n.d.-b).
So the free version answers yes or no, with no passage and no source, which is not enough to act on. Grammarly was not among the 15 systems Foltýnek et al. (2020) tested, and its pages give no figure for what share of copied text it finds, so its coverage could not be confirmed either way.
Which tool should I use for the check the night before?
For the text-matching check, EdCitation's Check plagiarism is the best tool for the job, because it does what the evidence above says a checker is for: it marks, in your own text, each passage found in published work or on the web, beside the source it came from, so each match can be read against the table above, and it shows the result only to the person who ran it, before any marker sees the paper. Turnitin's own guide says a checker does not check for plagiarism, and the Foltýnek test found that none of 15 systems found everything, so what a student needs is a report to read match by match with the source beside each one, not a percentage to hope about. EdCitation says plainly that a match is not proof of anything, either way. Check plagiarism is paid for in credits, 240 of which come with Pro each month ($8) and 720 with Max ($24). A check shows its cost in credits before it runs, and one that fails uses nothing. It needs no institution licence, unlike Draft Coach, and it shows the passages that Grammarly's free check does not.
The audit's reference checks are free, with no account. Verify references looks every entry up in the publisher's record, which a chatbot generating text cannot do, and reports each as verified, doubtful ("check this") or not found, flagging retracted papers; a source that could not be checked is never reported as not found. With the whole paper uploaded it also does step five, pairing citations and entries both ways, and References from a file, part of Pro, runs the same two checks from your file. Cite a source supplies any entry the audit shows is missing. EdCitation never writes or rewrites any part of a paper: the fix is yours.
Is reusing my own earlier work plagiarism?
Often yes, if you hand it in as new without permission. Roig (2015) defines self-plagiarism as reusing your own previously disseminated content and passing it off as new without telling the reader, and notes there is no consensus on how much text an author may recycle.
For coursework, the American Psychological Association (2022) states that some institutions treat submitting a paper written for one class as the assignment for another, without the current instructor's permission, as self-plagiarism, while building earlier classwork into a thesis may be allowed. Ask the instructor before submission, not the checker after it.
There is a practical trap too. Turnitin (n.d.-c) warns that submitting several drafts to an institution's private repository can leave the final draft matching itself at 100%, and advises submitting only the final draft. Draft Coach does not store drafts (Turnitin, n.d.-a).
Quick questions
Does a 0% similarity score mean my paper has no plagiarism?
No. Turnitin's own student guide says a low score does not always mean there is no plagiarism, and the Foltýnek test found that none of 15 systems caught manually paraphrased text at a satisfactory level. Compare each paraphrase with its source.
Can I use Turnitin on my own paper before submitting?
Only where your institution has licensed Draft Coach and switched it on, in Google Docs or in Word online. It gives three similarity reports per draft and does not store the draft.
Is Grammarly's plagiarism checker free?
The check on Grammarly's page is free and reports whether duplicate content was found. Highlighted passages with sources are a feature of its paid plans, and Grammarly's support pages say the checker is not available on a Free account.
Does changing a few words in a sentence avoid plagiarism?
No. Roig's guide describes swapping a word or two, reordering, or changing tense or voice as cosmetic changes that are not paraphrasing. A paraphrase needs your own words, your own sentence structure and a citation.
Is it plagiarism to hand in an essay I wrote for another module?
It can be treated as self-plagiarism. The APA Style guidance notes that some institutions count submitting one class's paper for another, without the current instructor's permission, as exactly that. Ask before you reuse it.
Is there a free way to check my citations before submitting?
Yes. Upload the whole paper to EdCitation's Verify references, free and without an account: each in-text citation is paired with its entry, each entry with a citation, and every entry is looked up in the publisher's record, so a citation with no entry, or an entry whose source cannot be found, shows up where a text-matching check sees nothing.
References
- American Psychological Association. (2022). Plagiarism. APA Style. https://apastyle.apa.org/style-grammar-guidelines/citations/plagiarism
- Foltýnek, T., Dlabolová, D., Anohina-Naumeca, A., Razı, S., Kravjar, J., Kamzola, L., Guerrero-Dib, J. G., Çelik, Ö., & Weber-Wulff, D. (2020). Testing of support tools for plagiarism detection. International Journal of Educational Technology in Higher Education, 17, Article 46. https://doi.org/10.1186/s41239-020-00192-4
- Grammarly. (n.d.-a). Plagiarism checker. Retrieved September 22, 2026, from https://www.grammarly.com/plagiarism-checker
- Grammarly. (n.d.-b). Plagiarism Checker user guide. Grammarly Support. Retrieved September 22, 2026, from https://support.grammarly.com/hc/en-us/articles/115000091452-Plagiarism-Checker-user-guide
- Grammarly. (n.d.-c). I do not see the plagiarism checker among the options. Grammarly Support. Retrieved September 22, 2026, from https://support.grammarly.com/hc/en-us/articles/115000090672-I-do-not-see-the-plagiarism-checker-among-the-options
- Pecorari, D. (2003). Good and original: Plagiarism and patchwriting in academic second-language writing. Journal of Second Language Writing, 12(4), 317–345. https://doi.org/10.1016/j.jslw.2003.08.004
- Roig, M. (2015). Avoiding plagiarism, self-plagiarism, and other questionable writing practices: A guide to ethical writing. Office of Research Integrity, U.S. Department of Health and Human Services. https://ori.hhs.gov/avoiding-plagiarism-self-plagiarism-and-other-questionable-writing-practices-guide-ethical-writing
- Turnitin. (n.d.-a). Turnitin Draft Coach FAQ. Turnitin Guides. Retrieved September 22, 2026, from https://guides.turnitin.com/hc/en-us/articles/28423411707533-Turnitin-Draft-Coach-FAQ
- Turnitin. (n.d.-b). Understanding your Draft Coach reports. Turnitin Guides. Retrieved September 22, 2026, from https://guides.turnitin.com/hc/en-us/articles/21993429763469-Understanding-your-Draft-Coach-reports
- Turnitin. (n.d.-c). Understanding the similarity score for students. Turnitin Guides. Retrieved September 22, 2026, from https://guides.turnitin.com/hc/en-us/articles/23713493434253-Understanding-the-similarity-score-for-students
- Turnitin. (2021). Understanding the Turnitin Similarity Report: A student guide. https://help.turnitin.com/Resources/PDF/understanding_the_turnitin_similarity_report-a_student_guide.pdf