Does Turnitin Check PDF Files? What Every Student Needs to Know

Yes — Turnitin accepts PDF files. But there is a catch that trips up a significant number of students every submission cycle: Turnitin can only read text-based PDFs. If your PDF is a scan, an image, a form, or was created with certain software, Turnitin either rejects it outright or produces a misleading 0% similarity score that has nothing to do with your paper's actual originality.

What file types does Turnitin accept?

Turnitin supports a wide range of formats beyond PDF. The full list of accepted file types includes:

Microsoft Word (.doc, .docx)
PDF (.pdf) — text-based only
PowerPoint (.ppt, .pptx, .pps, .ppsx)
Rich Text Format (.rtf)
Plain text (.txt)
HTML (.html, .htm)
OpenOffice Text (.odt)
WordPerfect (.wpd)
Google Docs (via Google Drive integration)

Formats that are not accepted include Apple Pages files, macro-enabled Word documents (.docm), and Microsoft Works files. When in doubt, Word (.docx) is the safest and most reliable format — it is what Turnitin processes most consistently.

Text-based PDFs vs. scanned PDFs — the critical difference

Not all PDFs are equal. There are two fundamentally different types:

Text-based PDFs contain real, selectable text generated from a word processor or document software. When you open one and try to highlight a sentence, you can select individual words. Turnitin can extract and analyse this text the same way it processes a Word document.
Scanned PDFs (image-based PDFs) are photographs or scans of a physical page. The file contains images of text, not actual text characters. Turnitin cannot read them. If you try to highlight text in a scanned PDF and nothing selects, that is the test — Turnitin will face exactly the same problem.

The easiest way to check before you submit: open your PDF, try to highlight and copy a sentence, and paste it into Notepad or any plain text editor. If readable text appears, your PDF is fine. If nothing pastes, or you get garbled characters, Turnitin will not be able to process it properly.

What Turnitin will reject or fail to process

Beyond scanned PDFs, several other PDF types cause problems:

Scanned or image-based PDFs — no selectable text, Turnitin cannot read them
Password-protected PDFs — encrypted or read-only files are rejected at upload
PDF forms — interactive form-field PDFs are not processed correctly
PDF portfolios — PDFs containing multiple embedded files inside one container
PDFs with “Fast Web View” enabled — an Adobe optimisation setting that causes upload failure in some Turnitin integrations
PDFs exported from LaTeX or LibreOffice — these sometimes produce non-standard character encodings that Turnitin cannot extract reliably, which can reduce the accuracy of similarity detection

What actually happens when you submit a bad PDF

There are two outcomes depending on the platform:

Rejection at upload. Turnitin checks whether it can extract at least 20 words of readable text from the file. If it cannot, the submission is rejected with an error along the lines of: “You must submit more than 20 words of text.” This is the most common outcome for scanned PDFs — the file never gets processed at all.

A false 0% similarity score. In some cases, particularly with certain platform integrations, a scanned PDF slips through the upload stage but Turnitin finds no text to compare. The result is a 0% similarity score — not because the paper is original, but because Turnitin could not read any of it. This is a problem in both directions: neither the student nor the instructor can trust the result, and the submission may be considered invalid.

As Leeds Beckett University notes in their student guidance, a 0% result from a PDF submission should always prompt a check on whether the file was actually text-based before drawing any conclusions from the score.

File size, page, and word count limits

Maximum file size: 100 MB (plain text .txt files: 2 MB)
Maximum pages: 800 pages
Minimum readable text: 20 words

For the vast majority of student assignments these limits are not a practical concern. They become relevant for submissions like theses, dissertations, or files with embedded high-resolution images.

PDF vs. Word — does your format affect your similarity score?

For properly created text-based PDFs, there is no meaningful difference in how Turnitin detects similarity compared to a Word document. The matching algorithm operates on extracted text regardless of the source format.

One minor technical difference worth knowing: PDFs can produce slightly different word counts in Turnitin compared to Word documents, because PDF extraction sometimes includes text from headers, footers, or footnotes differently. This affects the displayed word count in the report but does not materially affect your similarity percentage. For consistent results, Boston University's Turnitin guidance recommends submitting Word documents where possible — particularly for students using LaTeX, who should consider exporting to Word or using a LaTeX-to-Word converter before submitting.

If you only have a scanned PDF: what to do

If your source material is a scan and you need to submit it through Turnitin, you have a few options:

Use OCR to convert it. Optical Character Recognition (OCR) software reads the image of text and converts it into real, selectable characters. Google Drive does this for free — upload your scanned PDF, right-click it and open with Google Docs, and it will convert the text automatically. You can then export as a Word document or PDF. Adobe Acrobat Pro also has built-in OCR under Tools > Scan & OCR.
Retype the content into Word. For shorter documents, the most reliable option is simply typing the content into a Word document yourself.
Submit a Word file instead. If your institution accepts both formats, Word is always the safer choice.

Submitting to AIPlagGuides — PDF and Word both accepted

If you want to check your Turnitin similarity or AI score before your institution does, we accept the same file formats Turnitin supports — including text-based PDFs, Word (.doc and .docx), and most other standard document formats. Upload your file, receive the same Turnitin report your lecturer will see, and know exactly where you stand before your deadline. Just make sure your PDF has selectable text — if you can copy and paste from it, we can run it.

Frequently asked questions

Does Turnitin accept scanned PDF files?

No. Turnitin can only process PDFs that contain real, selectable text. Scanned PDFs are images of text, not actual text, so Turnitin cannot extract or analyse them. Submitting a scanned PDF will either result in an upload error or a false 0% similarity score that does not reflect the actual content of your paper.

What is the maximum file size Turnitin accepts?

100 MB for most file types, and 2 MB for plain text (.txt) files. The maximum is 800 pages. For most student assignments these limits are not a concern, but they can be relevant for long dissertations or files with embedded images.

Is my similarity score affected by submitting a PDF instead of a Word document?

Not meaningfully, as long as the PDF is text-based. Turnitin applies the same matching algorithm to text extracted from both formats. The only difference is a minor word-count discrepancy that sometimes appears due to how PDF text extraction handles headers and footnotes. This does not affect the similarity percentage.

How do I know if my PDF is text-based or scanned?

Open the PDF and try to highlight and copy a sentence from it. If you can select individual words and paste readable text into a text editor, it is text-based and Turnitin can process it. If nothing selects, or the pasted result is garbled characters, it is likely a scanned or image-based PDF that Turnitin will not be able to read.