Turnitin Similarity Report: How to Reduce Your Score

The first time I saw a Turnitin similarity report on my own work, I panicked. The number said 27%. More than a quarter of my thesis chapter was highlighted in different colours, with source matches linking to papers I had cited, a conference proceeding I published last year, and a few websites I had never even visited.

My immediate thought was: I plagiarized 27% of my thesis. That is not what it means. But it took me a while to understand that, and it took me even longer to figure out how to actually bring the number down.

If you are staring at a Turnitin report right now wondering what the colours mean, why your score is so high, or how to fix it before your deadline, this post walks through all of it.

What Is a Turnitin Similarity Report?

A Turnitin similarity report is a document generated by the Turnitin plagiarism detection system that shows how much of your submitted text matches content in its database. The database includes published academic papers, theses and dissertations from universities worldwide, web pages, books, and previously submitted student work.

When you submit a document to Turnitin, the system compares your text against everything in that database. Every phrase, sentence, or passage that matches an existing source gets highlighted and linked to the matching source. The total percentage of your text that matches anything in the database is your similarity index.

The similarity report is sometimes called a Turnitin plagiarism report, an originality report, or simply a Turnitin report. These all refer to the same thing. The key word to understand is “similarity.” Turnitin measures similarity, not plagiarism. The system does not know whether you copied, paraphrased poorly, quoted properly, or just happened to use the same phrase as someone else. It only knows that the text matches.

Whether that match constitutes plagiarism is a human decision. Your supervisor, your examiner, or the journal editor reads the report and decides whether the matches are legitimate (properly cited quotes, standard phrases, your own prior work) or problematic (unattributed copying, close paraphrasing without citation, excessive textual overlap).

How to Read a Turnitin Similarity Report

The report is colour-coded. Each colour represents a different source that your text matches. If a paragraph is highlighted in red, it means that paragraph matches a specific paper in the database. If another section is highlighted in blue, it matches a different source. The colours just help you distinguish between sources.

On the right side of the report, you will see a list of all matched sources, ranked by how much of your text they account for. Source 1 might account for 6% of your total similarity. Source 2 might account for 4%. And so on. These individual source percentages are just as important as the total similarity index, because a 20% overall score where no single source exceeds 2% is very different from a 20% score where one source accounts for 15%.

The overall similarity index is the number at the top of the report. This is the percentage that journals and universities look at first. But it is a blunt instrument. It counts everything: quoted text in quotation marks, your reference list, common phrases like “the results of this study indicate that,” and text from your own previously published conference papers. All of it gets counted in that top-line number.

This is why you should never panic about the overall number alone. You need to look inside the report and understand what is actually being matched.

What the Similarity Index Colours Mean in Practice

Turnitin uses a colour scale for the overall similarity index to give a quick visual indication of the score range.

Blue (0%). No matching text found. This is rare for any academic document because even common phrases and reference formatting will generate small matches.

Green (1 to 24%). The most common range for properly written academic work. A score in this range does not automatically mean there are no issues, but it is within the normal range. Most journals and universities consider scores under 15 to 20% acceptable.

Yellow (25 to 49%). This signals that a significant portion of text matches existing sources. Some of this may be legitimate (quotes, methodology descriptions, reference lists), but a score in this range usually requires investigation and revision before submission.

Orange (50 to 74%). A large portion of the text matches existing sources. This almost always indicates a problem that needs to be addressed before submission.

Red (75 to 100%). The majority of the text matches existing sources. This typically indicates direct copying or extremely close paraphrasing from one or more sources.

These ranges are guidelines, not rules. A 22% score with properly cited direct quotes might be perfectly fine. A 12% score where the matches are all unattributed close paraphrases might be a serious problem. The number tells you where to look. The content of the matches tells you whether there is an actual issue.

How Journals Use Turnitin Similarity Reports

An increasing number of academic journals run submitted manuscripts through Turnitin or a similar plagiarism detection system as part of their editorial screening process. This happens before peer review, usually at the desk review stage when the editor first evaluates the submission.

Most journals have an internal threshold for the similarity index. This threshold varies, but common benchmarks are 15% or 20%. If your manuscript scores below the threshold, the Turnitin report is noted and the paper proceeds to peer review. If your manuscript scores above the threshold, the editor will look at the report in detail.

What happens next depends on what the editor finds. If the matches are mostly properly cited quotes and standard phrases, the editor may still send the paper to review. If the matches indicate close paraphrasing without attribution, or significant overlap with a single source, the editor will likely return the manuscript with a request to revise and resubmit. In severe cases, particularly when large sections are copied directly, the manuscript is rejected.

Some journals are transparent about their threshold. You will find it in the author guidelines: “Manuscripts with a similarity index above 20% will be returned to the author for revision.” Others do not publish a specific number but still use one internally. If you cannot find a published threshold, targeting below 15% is a safe practice for most Scopus and Web of Science indexed journals.

Journals also look at the individual source percentages. A manuscript with a 15% overall score where one source accounts for 10% of the matches is more concerning than a 15% score spread across 30 different sources at less than 1% each. High overlap with a single source suggests either close paraphrasing of that one paper or unattributed borrowing, both of which editors take seriously.

How Universities Use Turnitin Reports for Thesis and Dissertation Submissions

Most universities now require students to submit their thesis or dissertation through Turnitin before or alongside the formal submission. The similarity report is reviewed by the supervisor, the examination committee, or the graduate school office.

University thresholds vary more than journal thresholds. I have seen policies ranging from 10% to 30%, depending on the institution, the department, and the degree level. Some universities set different thresholds for different chapters. A literature review chapter might be allowed a higher similarity index than a methodology or discussion chapter, because the literature review inherently involves describing other people’s work.

When a thesis exceeds the university’s threshold, the typical outcome is that the student is asked to revise the flagged sections before the thesis is accepted for examination. In some cases, the supervisor handles this informally, asking the student to paraphrase the flagged passages and resubmit the Turnitin report showing the improved score. In more formal cases, the graduate school may require a written explanation of the matches and a revised version.

The worst-case scenario, which is rare but real, is an academic misconduct investigation. This happens when the Turnitin report reveals extensive verbatim copying from sources without attribution. The investigation process is stressful, takes months, and can result in penalties ranging from a requirement to rewrite to, in extreme cases, revocation of the degree. This is why checking your Turnitin similarity report yourself before submitting is so important. Fix the problems on your own terms, not under investigation.

Why Your Similarity Index Is Higher Than You Expected

Most researchers are surprised by their Turnitin score the first time they see it. Here is why it is probably higher than you think it should be.

Your reference list is being counted. Turnitin scans your entire document, including the reference list. If you have 150 references formatted in APA style, many of those reference entries will match other documents that cite the same sources. This can add several percentage points to your overall score. Some universities allow you to exclude the reference list from the scan. If yours does, make sure that setting is enabled.

Quoted text is being counted. Even if you used proper quotation marks and cited the source, Turnitin still highlights the quoted text as a match. It does not distinguish between attributed quotes and unattributed copying. You can usually filter out quoted text in the report settings, which gives you a more accurate picture of your actual paraphrasing issues.

Your own published work is in the database. If you published a conference paper or a journal article before writing your thesis, that published text is in Turnitin’s database. When your thesis describes the same research using similar language, it matches against your own earlier work. This is a self-plagiarism flag, and it is one of the most common sources of unexpectedly high similarity scores for postgraduate students.

Common phrases add up. Phrases like “the purpose of this study is to,” “the results indicate that,” and “a sample of 300 participants was recruited” are used in thousands of academic documents. They are not plagiarism. They are standard academic phrasing. But Turnitin counts them, and across a 60,000 word thesis, these small matches accumulate.

Your literature review is doing most of the heavy lifting. As with paraphrasing issues in general, the literature review is almost always where the bulk of the similarity comes from. You are summarizing other people’s work, and unless your paraphrasing is genuinely different in structure and wording from the original, Turnitin will flag it.

How to Reduce Your Turnitin Similarity Score Through Paraphrasing

Once you understand what the report is showing you, reducing the score is a writing task. Here are the specific techniques that work.

Open the report and identify the real problems. Ignore the reference list matches, the properly cited direct quotes, and the common-phrase matches. Focus on the highlighted passages where you paraphrased a source but stayed too close to the original wording. These are the matches that matter, and these are the ones you need to rewrite.

Use the read-close-write method. Read the source passage. Close it. Write the idea from memory in your own words. This forces you to use your own sentence structure because your memory stores meaning, not exact phrasing. Then check the original to make sure you got the content right.

Change the sentence structure, not just the words. If the original says “The study found a significant relationship between X and Y,” do not write “The research discovered a notable connection between X and Y.” That is synonym swapping and Turnitin still catches the structural match. Instead, restructure completely: “X and Y were found to be significantly related in this study.” The subject changed. The verb changed. The sentence order changed. That is real paraphrasing.

Synthesize multiple sources into one passage. Instead of paraphrasing Source A in one sentence and Source B in the next, combine them: “While Author A found that X increases under condition Y, Author B reported the opposite trend, and more recent work by Author C suggests the relationship may be moderated by Z.” This synthesis is entirely your own structure and is almost impossible for Turnitin to match to any single source.

Add your own interpretation after every paraphrased finding. “This finding is relevant to the current study because…” or “However, a limitation of this evidence is that the sample was restricted to…” These analytical sentences are 100% original. They bring your similarity percentage down and they make your writing better.

Rewrite your methodology from scratch if it matches your own prior publications. Do not copy from your conference paper. Describe the same method in different language with a different sentence structure. It is tedious but necessary for avoiding self-plagiarism flags.

Exclude reference lists and quoted text from your personal assessment. Most Turnitin settings allow you to filter these out. The filtered score gives you a more honest picture of your actual paraphrasing quality. Fix the real issues first, and let the reference list and quotes be what they are.

Why Automated Paraphrasing Tools Do Not Solve Turnitin Problems

I know it is tempting. You have a flagged paragraph. You paste it into QuillBot or a similar tool. It rewrites it. The similarity match disappears. Problem solved.

Except it is not solved. Here is what you actually did.

You replaced one problem with two. The paraphrased text might not match the original source anymore, so your similarity score drops. But the paraphrased text was generated by AI, which means it now has the statistical patterns that Turnitin AI Checker detects. You went from a plagiarism flag to an AI flag. That is not progress.

On top of that, automated paraphrasing tools frequently change meaning. “Significant correlation” becomes “important connection.” “The participants were randomly assigned” becomes “The people were given random roles.” These are not the same thing. Your examiner or reviewer will notice that the terminology is wrong, and that undermines your credibility more than a similarity match would.

If you need help paraphrasing, get human help. Either do it yourself using the techniques above, or use a professional academic paraphrasing service where a real editor with subject knowledge rewrites the flagged sections by hand.

How to Get a Turnitin Similarity Report Before You Submit

Checking your similarity score before submission is one of the simplest things you can do to avoid problems. Do not wait for the journal or university to run the report and find issues. Run it yourself first.

If you have institutional access to Turnitin through your university, you can submit your document directly and generate a report. Many universities allow students to run multiple drafts through Turnitin before the final submission. Ask your supervisor or your graduate school office how to access this.

If you do not have institutional access, or if you want a report independent of your university’s system, you can order a Turnitin similarity report through editing services. PM Proofreading generates official Turnitin similarity reports at US$8 per report. You can order a report before paraphrasing to identify the problem areas, and another report after paraphrasing to confirm the improvement.

Running the report early gives you time to fix issues at your own pace instead of scrambling after a rejection or revision request.

Need to check or reduce your Turnitin similarity score? Upload your manuscript and get a quote. PM Proofreading’s paraphrasing service rewrites flagged sections by hand. Turnitin similarity reports available at US$8 each. Paraphrasing priced at US$7.50 per 500 words.

What Similarity Score Should You Aim For?

There is no universal number. It depends on where you are submitting.

For most Scopus and Web of Science indexed journals, below 15% is a safe target. Some journals in medicine, engineering, and law are stricter and want below 10%. If your target journal publishes a specific threshold in its author guidelines, follow that. If it does not, aim for 15% or below.

For university thesis submissions, check your graduate school’s policy. Thresholds range from 10% to 30% depending on the institution. Some departments are more lenient than others. Your supervisor will know the informal expectations even if the formal policy allows a higher number.

Remember that some similarity is normal. A score of 0% is almost impossible for any academic document and would actually be suspicious. Direct quotes, reference lists, standard phrases, and common methodology descriptions all generate legitimate matches. The goal is not to eliminate similarity entirely. The goal is to make sure the matches that remain are legitimate and properly attributed.

If your score is above your target and the matches are mostly from poorly paraphrased sections, focus on the top five or six flagged passages. Rewriting those usually brings the overall score down significantly because they account for the largest individual matches.

Conclusion: The Report Is a Tool, Not a Verdict

A Turnitin similarity report tells you one thing: how much of your text matches existing sources. It does not tell you whether you plagiarized. It does not evaluate your research. It does not know whether you cited properly or forgot to. It is a measurement tool, and like all measurement tools, it is only useful if you understand what it is measuring.

The researchers who have the best experience with Turnitin are the ones who check their own reports before submission, understand what the highlighted sections actually mean, and fix the genuine paraphrasing issues before anyone else sees the report. That is the difference between a stressful scramble after a rejection and a clean submission that moves straight to review.

Check your report. Read the matches. Fix what needs fixing. Submit with confidence.

PM Proofreading offers professional academic paraphrasing, journal manuscript editing, thesis editing, and AI humanizing for international researchers. Turnitin similarity reports at US$8. Every editing order includes a free language editing certificate. Upload your manuscript and get a quote today.

Frequently Asked Questions

What is a Turnitin similarity report?

A Turnitin similarity report is a document generated by the Turnitin plagiarism detection system that shows what percentage of your submitted text matches content in its database of published papers, theses, websites, and books. The report highlights matching passages in colour and links each match to its source. The overall percentage at the top is called the similarity index. It measures textual overlap, not plagiarism. Whether a match is problematic depends on context, citation, and the judgment of the reader.

What is a good Turnitin similarity score for a journal submission?

Most Scopus and Web of Science indexed journals expect a similarity index below 15 to 20%. Some journals in medicine and engineering require below 10%. If your target journal specifies a threshold in its author guidelines, follow that number. If no threshold is published, aiming below 15% is a safe practice. Keep in mind that some similarity is normal from properly cited quotes, reference lists, and standard academic phrases. The goal is not 0%. The goal is that all remaining matches are legitimate and properly attributed.

Does a high Turnitin score mean I plagiarized?

Not necessarily. The Turnitin similarity index measures textual overlap, not intent. A high score can result from properly cited direct quotes, matches to your own previously published work (self-plagiarism), common academic phrases, your reference list, or close paraphrasing that stayed too near the original wording. Whether the matches represent actual plagiarism is a human judgment made by your supervisor, examiner, or journal editor after reviewing the full report. That said, a high score should always be investigated and addressed before submission.

How can I reduce my Turnitin similarity score?

Focus on the passages with the highest individual source matches. Use the read-close-write method: read the source, close it, and rewrite the idea in your own words with a completely different sentence structure. Do not swap synonyms. Synthesize multiple sources into single passages instead of paraphrasing them one by one. Add your own analytical commentary after paraphrased findings. Exclude reference lists and quoted text from your assessment to see the real paraphrasing issues. If you need help, a professional academic paraphrasing service can rewrite flagged sections by hand.