Plagiarism check for a bachelor’s thesis: before you hand in your thesis, you should check whether accidental plagiarism, missing citations or AI-generated passages are hiding in your text. Many students underestimate how quickly unintentional borrowing happens, and only hear about the problem after submission.
This guide shows you step by step how to review your bachelor’s thesis before you submit, how to read the report and what to do when matches show up. Mimir Mentor is an AI-supported platform for academic work that combines plagiarism detection, AI detection and text correction in a single step.
Plagiarism check for a bachelor’s thesis: process, timing, cost and institutional checks
For a bachelor’s thesis, the plagiarism check is above all a final quality check before submission: run a final check once the text, footnotes and bibliography are complete; you can also review sections earlier. Allow a buffer of 3 to 5 days so that you can assess matches, add sources and run a second pass if needed.
| Question | Short answer | What you should actually do |
|---|---|---|
| When should you check? | After the final draft, but before you submit the PDF. | Plan for a buffer of 3 to 5 days, especially for bachelor’s and master’s theses. |
| What should you check? | Plagiarism, paraphrases that stay too close, AI passages and unsupported claims. | Do not just look at the score; look at every flagged passage in context. |
| What does it cost? | A free scan is enough for a first assessment, the premium report for detailed work. | Use the free scan as a pre-check and the detailed report to revise the key passages. |
| Does your university check too? | Many institutions run their own check after submission or reserve the right to do so. | Run your own check beforehand, because that is the only point at which you can still correct things. |
If you are unsure afterwards, read Similarity score explained and Forgot to cite a source and AI text at university as well.
Why check for plagiarism before submission?
Many institutions now check bachelor’s theses with plagiarism software or explicitly reserve the right to do so. Whether your thesis is scanned automatically depends on the institution, the department and the assessment process. So the decisive question for you is not whether a check happens, but whether you spot the problematic passages yourself before you submit.
The problem: plagiarism is often unintentional. You paraphrase a source but forget the footnote. You reuse a phrase you thought was your own, but it came from a source. Or you use AI tools whose output happens to match existing texts. The various types of plagiarism show how many forms the problem can take.
Checking in advance gives you the chance to find and correct such passages before your institution does. Keep in mind: your university checks after submission. You should check before. Which providers detected copy-paste, paraphrases and translations most reliably is shown in our comparison of twelve plagiarism checkers.
With the declaration of authorship you formally confirm that your bachelor’s thesis is your own work and that all sources are cited correctly. A breach can be treated as academic misconduct, with consequences up to and including expulsion.
Typical plagiarism traps in bachelor’s theses
Certain mistakes come up particularly often in bachelor’s theses. If you know these traps, you can avoid them deliberately:
Paraphrasing plagiarism
You restate the content of a source in your own words but stay too close to the original. The sentence structure, the key terms or the sequence of arguments are almost identical. Without a citation, that is paraphrasing plagiarism.
Missing citations
You cite in the text but forget the entry in the bibliography, or the other way round. A footnote without a complete bibliographic reference can also count as sloppy source work.
Self-plagiarism
You reuse passages from your own term paper or proposal without marking them as such. That is plagiarism too, because the declaration of authorship applies afresh to every assessed piece of work. Read more in our guide to self-plagiarism.
AI-generated passages
You drafted parts with ChatGPT and edited them lightly. Institutions now check not only for plagiarism but also for AI-generated text. Undisclosed use of AI can be treated as academic misconduct.
The most common cause of plagiarism in bachelor’s theses is not bad intent, but time pressure and a lack of care with sources. Plan enough buffer for the final check.
Mimir data point: In a seed-based sample of 250 premium plagiarism checks from April 2026, 93.6 percent of the flags for closeness to a source were paraphrase flags. For a bachelor’s thesis that means: do not only check verbatim borrowings, but pay particular attention to your rewritten theory, literature review and methodology passages.
Check your bachelor’s thesis for plagiarism and AI passages now
How to check your bachelor’s thesis step by step
A thorough plagiarism check takes more than an upload. Here is how to work through it systematically:
- Finish the document: Complete your bachelor’s thesis in terms of content. For the final scan, complete the bibliography and footnotes first. Earlier section-level checks can still help. Otherwise you will produce unnecessary false alarms.
- Upload to Mimir Mentor: Upload your PDF or DOCX to mimir-mentor.com. The free document scan immediately gives you an overview: the number of plagiarism passages, AI matches and corrections.
- Work through the detailed report: The premium report shows you at sentence level which passages are flagged as plagiarism, AI-generated or unsupported claims. Every match shows the original source (for plagiarism) or the type of problem.
- Assess the matches: Not every match is genuine plagiarism. Correctly cited passages, technical terms and standard phrasing can all trigger matches. What matters is whether the source is cited correctly.
- Fix the problems: Add missing sources, rewrite passages that paraphrase too closely and review AI flags against your writing process and your institution’s disclosure rules. Use the built-in literature search to find suitable references.
- Check style and grammar: Use text correction for grammar, academic style and consistency. That way your thesis is not only free of plagiarism but also clean in its language.
- Second pass: After the corrections it is worth running another scan to make sure every problem has been resolved.
Reading the report: what does the similarity score mean?
The similarity score shows the percentage of your text that matches the reference database. Important: a high score does not automatically mean plagiarism. A low score does not automatically mean everything is fine.
| Similarity score | Assessment | Typical cause | What to do |
|---|---|---|---|
| Low score | Low score; review still needed | Technical terms, standard phrasing, short phrases | Review the matches and check for missing citations |
| Many small matches | Not automatically acceptable | Correctly cited passages, frequently used definitions | Check the matches individually: is every source cited correctly? |
| Several substantial matches | Needs contextual review | Possibly paraphrases that stay too close, missing citations | Work through every match and add sources or rewrite |
| Extensive matching text | Not a verdict by itself | Extensive borrowed text, copy-paste passages | Examine the sources and revise any unattributed borrowing |
The score on its own says little. What matters is what it is made up of. A match on a correctly cited quotation is harmless. A match on an unmarked paraphrase is not. That is why it is worth looking at the detailed report.
You will find more on how this works technically in our guide How does plagiarism detection work?
What to do when the plagiarism check shows matches
Matches are no reason to panic. Most of them are quick to fix. Work through the flagged passages systematically:
| Type of match | Cause | Solution |
|---|---|---|
| Correctly cited but still flagged | The plagiarism software detects the match, but you cited the source correctly. | Check quotation formatting and attribution. A correctly cited match is not, by itself, plagiarism. |
| Missing citation | You paraphrased or quoted but forgot the footnote or the bibliography entry. | Add the source. Check both the footnote and the bibliography. |
| Paraphrase too close to the original | You rewrote a source but stayed too close to the original. | Rewrite it in your own words and cite the source. |
| Unsupported claim | A substantive assertion with no citation. | Find a suitable source through literature search and cite it. |
| AI flag | A section shows language patterns that are typical of AI text. | Review accuracy, authorship and the applicable AI policy. A flag alone is not proof, and rewording does not remove disclosure obligations. |
You will find tips on citing correctly in our article How to avoid plagiarism.
Rewrite flagged passages in academic language
Mimir Mentor offers two levels. For a bachelor’s thesis we recommend the premium report, because for a final thesis you should work through every flagged passage individually.
| Feature | Free document scan | Premium report |
|---|---|---|
| Plagiarism passages | Number of matches as an overview | Sentence-level detail view with source attribution |
| AI matches | Number of AI-flagged passages | Section-by-section analysis in the AI detector report |
| Unsupported claims | Number | Flagged in the text with suggestions |
| Corrections | Number of errors found | Full correction report with suggestions |
| Built-in tools | No | Literature search, rewriting help, text correction |
| Recommendation for a bachelor’s thesis | For a first assessment | For systematic revision before submission |
The free scan is useful for getting a first impression: are there any matches at all? How many? For thoroughly revising a bachelor’s thesis, the premium report makes sense, because there you can assess every match individually and fix it directly in the editor.
Checklist: submitting a bachelor’s thesis free of plagiarism
Use this checklist as your final check before submission:
- Bibliography complete: every source cited in the text has an entry.
- Footnotes complete: every paraphrase and every quotation has a citation.
- Direct quotations in quotation marks with a page reference.
- No copy-paste passages from sources without attribution.
- No passages carried over from your own earlier work without a reference (no self-plagiarism).
- No undisclosed AI-generated passages (check your institution’s AI policy).
- Plagiarism check and AI check run with Mimir Mentor.
- Every flagged passage either revised or assessed as harmless.
- Grammar and academic style checked.
- Declaration of authorship completed honestly and signed.
Mimir Mentor is GDPR-compliant, with servers located in Mainz, Germany. Your document is deleted completely after 30 days at the latest and is not added to any public database. More than 45,000 students already use the platform.
Good next steps are Similarity score explained, Forgot to cite a source and How to paraphrase.
Scientific Formulations in Minutes Seconds
FAQ: Common questions about the plagiarism check for a bachelor’s thesis
-
At what similarity score does my bachelor’s thesis become a problem?
There is no fixed threshold. What matters is not the score, but what it is made up of. A score of 15 % from correctly cited passages is harmless. A score of 5 % from unmarked borrowing can be plagiarism. Check every match individually.
-
Is the free plagiarism check enough for my bachelor’s thesis?
The free document scan gives you a first assessment (the number of matches). For a bachelor’s thesis we recommend the premium report, because there you can work through every flagged passage individually and fix it directly in the editor.
-
How long before submission should I run the check?
Plan the plagiarism check at least 3 to 5 days before submission. That gives you enough time to revise flagged passages carefully, add missing sources and run a second pass.
-
Will my university run a separate check as well?
Many institutions check submitted work with their own plagiarism software or explicitly reserve the right to do so. Whether the check runs automatically depends on the institution and the department. Checking in advance gives you the chance to fix problems beforehand.
-
What happens if plagiarism is found after submission?
The consequences range from a fail through the loss of an examination attempt to expulsion in serious cases. Even years later, plagiarism can still be discovered and an academic degree revoked.
-
Can I check my bachelor’s thesis more than once?
Yes. At Mimir Mentor your text is not added to a database. You can check your work as often as you like without later checks matching against your own submission.
-
Are direct quotations shown as plagiarism?
Yes, plagiarism software flags every match with the database, including correctly cited passages. That is not a problem as long as the source is cited correctly. In the detailed report you can mark these matches as harmless.
