How to Cite Preprints and arXiv Papers in Academic Work

TL;DR — The short version

• Always label preprints as such — use [Preprint] in your reference list so readers know the work hasn’t been peer-reviewed.
• Check for a peer-reviewed version first — if the paper has since been published in a journal, cite the final published version instead of the preprint.
• Cite the specific version — preprints can have multiple versions; include the version number (e.g., /v1) in your citation.
• APA format: Author, A. A. (Year). Title \[Preprint\]. Repository. DOI or URL
• MLA format: Author. "Title." _Repository_, Date. Preprint.
• Chicago author-date: Author. Year. "Title." Preprint, submitted Month Day. URL.
• Discipline matters — citing preprints is routine in physics and mathematics but controversial in clinical medicine.

What Is a Preprint? (And Why You’re Citing It)

A preprint is a version of a scholarly article made publicly available before it has undergone formal peer review. Preprint servers like arXiv, bioRxiv, and medRxiv allow researchers to share their findings rapidly with the academic community — sometimes months or years before a journal publishes the final version.

The key difference between a preprint and a peer-reviewed article is simple: preprints have not yet been evaluated by other experts in the field. The findings might be sound, or they might contain errors, methodological flaws, or incomplete analysis. That’s why preprints should never be treated as definitive proof — especially in sensitive areas like clinical research or public policy.

But here’s the reality: preprints are increasingly common. In 2025, more than 1.4 million preprints were posted across major servers. They’re essential reading for researchers who need the latest findings, and they’re increasingly accepted in many disciplines. The question isn’t whether to cite them — it’s how to cite them properly.

How to Cite a Preprint: Format Rules by Citation Style

APA Style (7th Edition)

APA treats preprints as unpublished manuscripts. The format follows this structure:

Reference List Entry:

Author, A. A. (Year). Title of manuscript [Preprint]. Repository Name. URL or DOI

Example:

Hampton, S., Rabagliati, H., & Sorace, A. (2017). Autism and bilingualism: A qualitative interview study [Preprint]. PsyArXiv. https://doi.org/10.31234/osf.io/76xfs

In-Text Citation:

Parenthetical: (Hampton et al., 2017)
Narrative: Hampton et al. (2017)

Key APA rules:

• Always include the [Preprint] label
• Use the repository name (arXiv, bioRxiv, etc.)
• Include the DOI if available (most servers assign DOIs)
• If no DOI exists, use the full URL
• Do not italicize the repository name

MLA Style (9th Edition)

MLA formats preprints similarly to other online sources:

Works Cited Entry:

Author Last, First. "Title of Preprint." Repository Name, Date of Posting. Preprint.

Example:

Patel, Raj. "Genomic Mapping Strategies." bioRxiv, 22 Feb. 2026. Preprint.

In-Text Citation:

(Patel) or (Patel 15)

Key MLA rules:

• Include the word “Preprint” at the end of the entry
• Format the date as Day Month Year
• Italicize the repository name
• If no author is available, start with the title

Chicago Style (17th Edition)

Chicago handles preprints differently depending on which system you use:

Author-Date System:

Author Last, First. Year. "Title of Preprint." Preprint, submitted Month Day. URL.

Notes-Bibliography System:

1. First Name Last Name, "Title of Preprint" (preprint, submitted Month Day, Year), URL.

Example:

Doe, John, and Alice Smith. 2026. "Quantum Computing Advances." Preprint, submitted January 15. https://doi.org/10.1234/dosomething

Key Chicago rules:

• Use “Preprint” or “unpublished manuscript” depending on system
• Include the submission date (not the access date)
• Provide the DOI or full URL

Harvard Style

Harvard formats preprints similarly to other online resources:

Reference Entry:

Author Last, Initial(s). [Year]. Title of preprint [online]. Available: URL (Accessed: Day Month Year).

Example:

Doe, J. [2026]. Quantum computing advances in machine learning [online]. Available: https://arxiv.org/abs/2401.12345 (Accessed: 2 Feb. 2026).

Key Harvard rules:

• Include [online] as part of the format
• Add the access date
• Use the full URL

The Versioning Problem: Why You Must Cite the Specific Version

One of the trickiest aspects of citing preprints is version management. Preprints are frequently updated, and authors may post multiple versions of the same paper before it’s published. Here’s how to handle it:

APA example with version:

Doe, J. (2026). Quantum computing advances [Preprint]. arXiv. https://arxiv.org/abs/2401.12345v1

MLA example with version:

Doe, John. "Quantum Computing Advances." arXiv, 15 Jan. 2026. Preprint.
— For a specific version, append /v2, /v3, etc. to the URL:
https://arxiv.org/abs/2401.12345v2

Harvard example with version:

Doe, J. [2026]. Quantum computing advances [online]. Available: https://arxiv.org/abs/2401.12345v1 (Accessed: 2 Feb. 2026).

The golden rule: Always cite the version you actually read and used. If you read version 2 of a paper, cite v2 — not v1, not the published version (unless it’s been published). This ensures your readers can find exactly the material you used.

Discipline Norms: When It’s Acceptable to Cite Preprints

Not all academic fields treat preprints the same way. Discipline norms vary dramatically:

Fields Where Preprints Are Standard

• Physics and mathematics: arXiv has been the dominant preprint server for over three decades. Citing preprints is routine and widely accepted. Researchers often read, cite, and build upon arXiv papers before formal peer review.
• Computer science: The culture around arXiv has shifted so heavily toward preprints that many computer science journals expect authors to cite arXiv versions.
• Mathematics and theoretical physics: These fields value speed of dissemination over formal review, so preprints are the primary way researchers establish priority.

Fields Where Preprints Are Growing But Controversial

• Biology and life sciences: bioRxiv is widely used, but many journals discourage citing preprints when a peer-reviewed version is available.
• Health sciences: medRxiv is growing rapidly, but clinical guidelines caution against using preprints for patient care decisions or public policy.
• Social sciences: PsyArXiv and SocArXiv are emerging, but acceptance is fragmented. Economics and political science embrace preprints more than sociology or anthropology.

Fields Where Preprints Are Often Discouraged

• Clinical medicine: The ICMJE (International Committee of Medical Journals) and other bodies strongly recommend citing only peer-reviewed “versions of record” for clinical research. Preprints may contain unverified clinical data that could affect patient outcomes.
• Public policy research: Policy documents should cite peer-reviewed sources to ensure findings are validated and reproducible.

When to Cite a Preprint (And When Not to)

Before you cite a preprint, ask yourself these questions:

✅ Good Reasons to Cite a Preprint

❌ When to Avoid Citing Preprints

How to Check if a Preprint Has Been Published

Here’s the critical workflow I recommend for every preprint you cite:

Step 1: Search for the Published Version

Where to look:

• Use Google Scholar to search the preprint title
• Check CrossRef (crossref.org) for DOI links
• Search the preprint server directly (many show “published in [journal name]” on the landing page)
• Ask your librarian if you’re unsure

The rule: If a preprint has been published in a peer-reviewed journal, always cite the published version, not the preprint. The published version represents the vetted, authoritative scientific record.

Step 2: Update Your Bibliography

If you cited a preprint in draft form and later discover the peer-reviewed version:

• Replace the preprint citation with the journal citation
• Keep the preprint citation only if you specifically discuss the preprint version itself

Step 3: Verify the Source

Before citing any preprint:

• Check the server’s credibility (is it a well-known, established server?)
• Verify the authors’ affiliations
• Review the methodology carefully
• Be cautious about drawing strong conclusions from unreviewed data

Quick Reference: Citation Examples Across Servers

Different preprint servers use slightly different formats. Here are examples for the most common platforms:

arXiv

APA: Doe, J. (2026). Quantum computing advances [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2401.12345
MLA: Doe, John. "Quantum Computing Advances." arXiv, 15 Jan. 2026. Preprint.
Chicago: Doe, John. 2026. "Quantum Computing Advances." Preprint, submitted January 15. https://doi.org/10.48550/arXiv.2401.12345

bioRxiv

APA: Doe, J. (2026). Genomic mapping strategies [Preprint]. bioRxiv. https://doi.org/10.1101/123456
MLA: Doe, John. "Genomic Mapping Strategies." bioRxiv, 22 Feb. 2026. Preprint.
Chicago: Doe, John. 2026. "Genomic Mapping Strategies." Preprint, submitted February 22. https://doi.org/10.1101/123456

medRxiv

APA: Doe, J. (2026). Clinical trial outcomes [Preprint]. medRxiv. https://doi.org/10.1101/654321
MLA: Doe, John. "Clinical Trial Outcomes." medRxiv, 10 Jan. 2026. Preprint.
Chicago: Doe, John. 2026. "Clinical Trial Outcomes." Preprint, submitted January 10. https://doi.org/10.1101/654321

Research Square

APA: Alayidh, F. S. et al. (2025). Direct-Acting Antiviral Therapy [Preprint]. Research Square. https://doi.org/10.21203/rs.3.rs-7285246/v1
MLA: Alayidh, F. S. et al. "Direct-Acting Antiviral Therapy." Research Square, 12 Mar. 2025. Preprint.
Chicago: Alayidh, F. S. et al. 2025. "Direct-Acting Antiviral Therapy." Preprint, submitted March 12. https://doi.org/10.21203/rs.3.rs-7285246/v1

Common Mistakes When Citing Preprints

Mistake 1: Citing a Preprint When a Peer-Reviewed Version Exists

Wrong: Citing a preprint when the paper has since been published in a journal.
Right: Always search for the peer-reviewed version and cite that instead. The published version is the authoritative standard.

Mistake 2: Forgetting the [Preprint] Label

Wrong: Doe, J. (2026). Quantum computing advances. arXiv. https://doi.org/10.48550/arXiv.2401.12345
Right: Doe, J. (2026). Quantum computing advances [Preprint]. arXiv. https://doi.org/10.48550/arXiv.2401.12345

The [Preprint] label is required by APA, Springer Nature, and most academic publishers. It ensures readers understand the work hasn’t been peer-reviewed.

Mistake 3: Using a DOI from an Old Version

Wrong: Citing .../v1 when you read version 2.
Right: Always cite the exact version you consulted. Append /v2, /v3, etc. to the URL.

Mistake 4: Treating Preprints as Peer-Reviewed

Wrong: “Smith et al. (2026) proved that X causes Y.”
Right: “Smith et al. (2026) reported findings suggesting X may cause Y, though the work remains unpublished and unreviewed.”

Preprints contain preliminary results. Be honest about their limitations.

Mistake 5: Mixing Up Repository Names

Wrong: Using “PubMed” as a preprint server (PubMed is a citation index, not a preprint server).
Right: Use the correct server name: arXiv, bioRxiv, medRxiv, Research Square, PsyArXiv, SocArXiv, etc.

The Academic Integrity of Citing Preprints

From an academic integrity perspective, citing preprints raises unique challenges. The ICMJE (International Committee of Medical Journals) states:

“Because preprints have not yet been peer reviewed, they should be treated with caution. They are not final versions and may be updated or corrected at any time.”

Key principles for academic integrity when citing preprints:

1. Transparency: Always label preprints with [Preprint] or “unpublished manuscript”
2. Verification: Check whether a peer-reviewed version exists before citing
3. Credibility: Evaluate the methodology carefully; preprints may contain errors
4. Context: Be honest about what the preprint can and cannot prove
5. Discipline norms: Follow field-specific guidelines; don’t cite preprints in fields where they’re discouraged

When to Prefer Peer-Reviewed Sources Over Preprints

Even when citing a preprint is acceptable, ask yourself: should I use a peer-reviewed source instead?

Always prefer peer-reviewed versions when:

• The paper has been published in a peer-reviewed journal since the preprint was posted
• The preprint is more than 2 years old
• The research affects clinical decisions or public policy
• Your institution or instructor requires peer-reviewed sources only

It’s okay to cite preprints when:

• No peer-reviewed version exists and the preprint is recent (≤1–2 years)
• You’re in a field where preprints are standard (physics, computer science)
• You’re analyzing the evolution of a paper from preprint to published
• The research topic is rapidly evolving and time-sensitive

Summary and Next Steps

Citing preprints and arXiv papers is straightforward once you understand the rules. The key elements are always the same — author, year, title, repository, and identifier — but the formatting varies by citation style and discipline.

Your next steps:

1. Check if a peer-reviewed version exists before citing any preprint
2. Label every preprint citation with [Preprint] or “unpublished manuscript”
3. Cite the specific version you read (include version numbers)
4. Follow discipline norms — some fields embrace preprints, others don’t
5. Update your bibliography if you find a peer-reviewed version later

Need help? Use our plagiarism checker to ensure your citations are properly formatted and your work meets academic integrity standards.

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