Quick Takeaways
Supplementary materials (also called supplemental materials) are additional files—datasets, code, videos, extended tables—that support your research article but are not essential to understanding its main findings. They enhance reproducibility, increase discoverability, and keep the main text focused. Key points: only include non-critical content, follow journal-specific guidelines, use standard formats (PDF, CSV, MP4), keep files under 10 MB when possible, reference every file in the main text, and include a README to guide readers. Poorly prepared supplementary materials can hurt your paper’s impact; well-organized ones boost credibility and citations.
Introduction: Why Supplementary Materials Matter
You’ve poured months into your research. Your dataset spans thousands of rows, your experiment generated dozens of high-resolution images, and your statistical analysis includes dozens of supplemental tables. But journal word limits force you to cut pages. Where does all this valuable content go?
Enter supplementary materials—the scholarly publishing solution for hosting extensive supporting information alongside your article. According to Elsevier and Springer Nature guidelines, supplementary files allow authors to publish “supporting applications, movies, animation sequences, high resolution images, datasets, sound clips and more” without cluttering the main text[1][2].
But supplementary materials are more than just a dumping ground. They serve critical functions:
- Transparency and Reproducibility: Provide raw data and detailed methods so others can verify your results[3]
- Enhanced Discoverability: Articles with supplementary material often rank higher in search results and attract more citations[4]
- Reader Engagement: Multimedia content (videos, animations) increases time on page and understanding[5]
- Space Management: Keep the main article concise while preserving important supporting content[6]
However, misuse of supplementary materials—such as placing essential findings in supplements to circumvent word limits—can backfire. As one study noted, “excessive use threatens the integrity of the scientific literature” when critical information is hidden[7].
This guide prepares you to decide what belongs in supplementary materials, format files correctly for major publishers, and submit professionally to maximize your article’s impact.
What Are Supplementary Materials? Definition and Purpose
Supplementary materials (sometimes called “supporting information” or “appendix online”) are files published alongside your main article that provide additional information not essential to understanding the core findings but valuable for deeper exploration.
Key Characteristics
- Non-standalone: The main article must be comprehensible without them[8]
- Peer-reviewed: Usually reviewed alongside your manuscript
- Published as-supplied: Most journals don’t edit or typeset supplementary files; they appear as you submitted them[9]
- Linked: Must be clearly referenced within the main text (e.g., “See Supplementary Table S1”)
- Permanent: Once published, they become part of the scholarly record and cannot be easily modified[10]
Common Types of Supplementary Materials
Based on publisher guidelines from Elsevier, Springer, Nature, and IEEE[1][2][5][11], typical supplementary files include:
| Category |
Examples |
Typical Formats |
| Data |
Raw datasets, spreadsheets, machine-readable files |
.csv, .xlsx, .txt |
| Multimedia |
Video clips, animations, audio recordings |
.mp4, .avi, .mp3 |
| Extended Tables |
Large tables exceeding journal limits |
.pdf, .docx, .xlsx |
| Additional Figures |
Extra plots, high-resolution images |
.tif, .png, .pdf |
| Code |
Software scripts, algorithms, simulations |
.py, .R, .m, .txt |
| Detailed Methods |
Protocols, derivations, technical appendices |
.pdf, .docx |
| Questionnaires |
Survey instruments, interview guides |
.pdf, .docx |
What NOT to put in supplementary materials: Essential findings, core arguments, or critical methodology that readers must understand to follow your paper. If removing the material would make the main text confusing or incomplete, it belongs in the main article[12].
Main Text vs. Supplementary Materials: Decision Guide
One of the most common questions authors ask: “Should this go in the main paper or in supplementary materials?” Use this decision framework:
Rule of Thumb: The Removal Test
Ask yourself: “If I removed this content entirely, would readers still understand the main contributions and conclusions?”
- Yes → Supplementary materials (supportive but not essential)
- No → Main text (critical to understanding)
Specific Scenarios
| Content Type |
Recommended Location |
Reason |
| Primary results and key findings |
Main text |
Core contribution |
| Large raw dataset (1000+ rows) |
Supplementary |
Too voluminous for main text |
| Additional control experiments |
Supplementary |
Supportive but not central |
| Video of experimental procedure |
Supplementary |
Demonstrates method without cluttering text |
| Extended literature review |
Supplementary |
Main review should be concise |
| Mathematical proofs |
Supplementary |
Detailed derivations belong in supplement |
| Questionnaire items |
Supplementary |
Interested readers can access full instrument |
| Secondary or exploratory analyses |
Supplementary |
Not central to main hypothesis |
| High-resolution versions of figures |
Supplementary |
Improves viewing experience |
Example: Suppose you conducted a psychology experiment with 50 participants. Your main text reports the key statistical findings (means, standard deviations, p-values). The supplementary materials would contain the complete raw data spreadsheet (participant_01_to_50_raw.csv), the full survey questionnaire (survey_items.pdf), and perhaps a video showing the experimental setup (setup_video.mp4).
Journal-Specific Formatting Guidelines: What You Need to Know
Supplementary material requirements vary significantly among publishers. Always check the target journal’s “Guide for Authors,” but here are common patterns:
File Format Recommendations
Based on guidelines from major publishers[1][2][5][11]:
- Text/Tables: PDF (best for preservation), DOCX, or TXT
- Data: CSV (most universal), XLSX
- Images: TIFF, PNG, PDF (avoid JPEG for scientific data—lossy compression)
- Code: Plain text files (.txt) or language-specific (.py, .R)
- Video: MP4 (H.264 codec) for broad compatibility
- Audio: MP3, WAV
Avoid: Proprietary formats that may become unreadable (e.g., SPSS .sav files should be exported to .csv for archiving).
File Size Limitations
- Ideal: Keep individual files under 10 MB[13]
- Common maximum: 20-50 MB per file[5][11]
- Total package: Often capped at 150 MB total (Nature, IOP)[5][14]
- Large datasets: Use external repositories (Zenodo, Figshare) and link from your article
From Nature’s guidelines: “Ensure that file sizes are as small as possible so that users can download them quickly. Images should be a maximum size of 640 x 480 pixels (9 x 6.8 inches at 72 pixels per inch).”[5]
Naming Conventions
- Use clear, descriptive names:
Supplementary_Table_S1_Descriptive_Statistics.pdf
- Avoid spaces; use underscores or hyphens:
Supplementary_Figure_S2_Scatterplot.png
- Number sequentially: S1, S2, S3… for figures, tables, datasets
- Include your surname or manuscript ID if requested:
Smith_TableS1.pdf
What Journals Do (and Don’t Do)
- They DO: Check file formats and basic readability during submission
- They DO NOT: Edit or typeset your supplementary files[9]
- They DO: Require you to cite each file in the main text
- They DO: Often impose strict limits on number and size of files
Common Mistakes Authors Make (and How to Avoid Them)
Based on analysis of publishing guidelines and expert recommendations[7][12][13], here are the most frequent errors:
Mistake 1: Hiding Essential Information in Supplements
Problem: Placing key findings or methodology in supplementary materials to bypass journal word limits, making the main paper incomprehensible.
Impact: Reviewers may reject; readers may miss important results; citation indices often ignore supplement-only references[7].
Solution: Use the “Removal Test” from above. If the paper cannot stand alone, restructure.
Mistake 2: Poor File Organization and Naming
Problem: Files named finalfinal_v3_updated.pdf, data1.xlsx, figure.jpg without context.
Impact: Readers (and reviewers) waste time deciphering files; may ignore your supplements entirely.
Solution: Adopt a clear naming convention and include a README.txt file explaining the structure[13].
Mistake 3: No README or Documentation
Problem: Sending a zip file with cryptic filenames and no explanation.
Impact: Your supplements become unusable; data cannot be interpreted; future reuse is impossible.
Solution: Include a brief README that describes:
- Overall project and file structure
- Purpose of each file
- How files relate to main text sections
- Software needed to open/view files
- Variable definitions for datasets
Mistake 4: Using Excessive or Unusual File Formats
Problem: Submitting files in obscure or proprietary formats that require special software.
Impact: Readers cannot access your content; reduces impact and reuse.
Solution: Stick to common, open formats (PDF, CSV, MP4). If you must use proprietary software, also export to a standard format[1].
Mistake 5: Exceeding Size Limits
Problem: Uploading a 500 MB video file that crashes the submission system.
Impact: Submission rejected or delayed; you’ll need to re-format and re-upload.
Solution: Compress files before uploading. For videos, reduce resolution to 1080p or lower. For large datasets, use a repository and provide a link instead[13].
Mistake 6: Forgetting to Reference Supplements in Main Text
Problem: Submitting supplements but never mentioning them in the article.
Impact: Journal staff may remove them as unreferenced; readers won’t know they exist.
Solution: In your manuscript, write: “Supplementary materials are available at [journal site] and include: Supplementary Table S1 (descriptive statistics), Supplementary Figure S2 (scatterplot), and Supplementary Dataset S3 (raw data).”
Step-by-Step: Preparing Supplementary Materials for Submission
Follow this workflow to create professional supplementary materials:
Step 1: Decide What to Include (Pre-Writing)
Before drafting your manuscript, plan your supplementary content. Ask:
- What data or materials are essential for reproducibility but too voluminous for the main text?
- What would other researchers want to access to understand or build upon your work?
- Does the journal have specific requirements (file types, size limits, number of files)?
Tip: Create a “supplementary materials outline” alongside your main article outline.
Step 2: Prepare Files with Proper Formatting
- Convert to standard formats (see table above)
- Compress files if needed (use
zip sparingly; some journals discourage it[1])
- Label clearly with S1, S2, S3 prefixes
- Create a README file explaining everything
- Test accessibility: Can someone with common software (Adobe Reader, Excel, VLC) open each file?
Step 3: Write the README
Your README is the most important supplementary file. Template:
Project: [Title]
Manuscript ID: [if assigned]
Corresponding author: [Name]
=== OVERVIEW ===
This supplementary material accompanies the article "[Article Title]" published in [Journal Name].
It contains:
- Supplementary Table S1: [Description]
- Supplementary Figure S2: [Description]
- Supplementary Dataset S3: [Description]
=== FILE DESCRIPTIONS ===
S1_Descriptive_Statistics.xlsx
- Contains means, standard deviations for all variables
- Sheet1: Demographic characteristics
- Sheet2: Primary outcome measures
S2_Scatterplot.png
- Scatterplot of variables X vs Y from Figure 3
- High-resolution version (1200 dpi)
S3_Raw_Data.csv
- Participant-level data for all 150 subjects
- Variables: ID, age, group, pre_score, post_score
- Missing values coded as -99
=== SOFTWARE REQUIREMENTS ===
- CSV files can be opened in Excel, R, Python, or any text editor
- XLSX requires Excel or compatible software
- PNG files can be viewed in any image viewer
=== CITATION ===
If you use these data, please cite the parent article:
Author et al. (2026). Article Title. Journal Name.
=== CONTACT ===
For questions, email: [email address]
Step 4: Reference Supplements in Main Text
In your manuscript, include a statement such as:
“Supplementary materials are available online. Supplementary Table S1 presents descriptive statistics for all variables. Supplementary Figure S2 shows the full scatterplot. Supplementary Dataset S3 contains the raw data underlying our analysis.”
Place this typically in the Methods or Results section, or as a footnote.
Step 5: Upload During Submission
During journal submission, you’ll find a section for “supplementary files” or “supporting information.” Upload each file separately (or as a single zip if allowed). Ensure:
- All files are correctly attached
- File order matches your README
- No personal information in file names (double-blind review)
Step 6: Post-Acceptance
Once your article is accepted, the journal will publish your supplementary files alongside it. Verify on the proofs that all links work and files are present.
Publisher-Specific Requirements: Quick Reference
While always checking the specific journal’s author guide, here are general patterns:
| Publisher |
Max File Size |
Preferred Formats |
Notes |
| Elsevier |
10-50 MB |
PDF, DOCX, XLS, CSV, MP4, AVI |
Requirements vary by journal; check specific guide[1] |
| Springer Nature |
10 MB recommended; total ~150 MB |
PDF, TXT, CSV, MP4 |
Journals may have stricter limits[2][5] |
| IEEE |
10 MB each |
PDF, DOC, JPG, TIF, MP4, MP3 |
Code acceptable; provide README[11] |
| Wiley |
10 MB recommended |
PDF, DOC, XLS, CSV, TIFF, MP4 |
Avoid ZIP when possible[9] |
| IOP |
50 MB each; total 150 MB |
PDF, DOC, XLS, CSV, MP4, AVI |
Specify supplementary materials during submission[14] |
Nature-specific: Images should be max 640×480 pixels at 72 dpi for web viewing[5].
Linking Supplementary Materials to Data Repositories
For very large datasets (hundreds of MB or GB), most journals recommend using external data repositories rather than uploading as supplementary files.
Recommended Repositories
How to Link
- Upload your dataset to the repository
- Obtain a DOI (digital object identifier)
- In your manuscript, write: “Raw data are available at https://doi.org/10.7717/peerj.1338“
- In supplementary materials, you can include a short file with the citation for the dataset
This approach ensures long-term preservation and makes your data findable via search engines (FAIR principles)[10].
Ethical and Practical Considerations
Data Availability Statements
Many journals now require a “Data Availability Statement” in the main article. This explains where readers can access data underlying the study. Supplementary materials count as a location, but you should also consider a public repository for maximum impact.
Sensitive or Confidential Data
If your research involves human subjects with confidential information:
- Anonymize data before sharing (remove names, IDs, exact addresses)
- Use controlled access: Some repositories allow you to require users to request access
- Check regulations: HIPAA (US health data), GDPR (EU personal data) impose restrictions
- Include a data use agreement if needed
Licensing and Reuse
- Apply a license to your supplementary materials to clarify how others may use them
- Common licenses: CC0 (public domain), CC-BY (attribution required)
- Avoid “all rights reserved” if you want wide reuse
Supplementary Materials Checklist
Use this before submitting your manuscript:
Content Decisions
Technical Preparation
Submission Process
Related Guides
To strengthen your overall research and publishing skills, explore these related resources:
Frequently Asked Questions
Q: Can I update supplementary materials after publication?
A: Generally no. Supplementary materials are published as-supplied and become part of the permanent record. Minor corrections may be allowed via errata, but major revisions typically require a new article version. This is why thorough preparation is critical[10].
Q: Do supplementary materials count toward citation metrics?
A: Content in supplementary materials is not indexed in major citation databases like Web of Science or Scopus, so citations to supplement-only material may not be counted[7]. Always place essential findings in the main text.
Q: What’s the difference between “supplementary materials” and “appendix”?
A: In journal articles, “supplementary materials” typically refers to online-only files kept separate from the main PDF. An “appendix” may appear within the main document or at the end. Some journals use the terms interchangeably. Check the specific journal’s style.
Q: How large can supplementary materials be? Can I upload my entire 2 GB dataset?
A: Most journals cap supplementary files at 10-50 MB each and total package ~150 MB. For larger datasets, use an external repository (Zenodo, Figshare) and include a link or DOI.
Q: Should I include my raw data or only processed/cleaned data?
A: Include both if space allows. Raw data provides transparency; cleaned data provides usability. Document all processing steps in your README.
Q: Do supplementary materials get peer-reviewed?
A: Yes, typically alongside the main manuscript. Reviewers may request additional data or clarification. Ensure your supplements are complete and well-organized before submission[1].
Q: Can I use supplementary materials to circumvent journal page limits?
A: Only for truly supplementary content. Journal editors and reviewers check for “essential content” hidden in supplements and may reject if the main text is not self-contained[7].
Q: Are there additional charges for supplementary materials?
A: Most traditional subscription journals do not charge extra. Some open-access journals may have fees for large supplementary packages. Check the journal’s fee schedule.
Q: How do I cite supplementary materials from another article?
A: Cite the main article, not the supplement directly. In your reference list, include the main article citation. In text, you might write: “Data from Smith et al. (2025) supplementary materials show…” but your reference is still the main article.
Conclusion: Supplementary Materials as a Professional Tool
Supplementary materials, when used correctly, are powerful tools that enhance your research article’s credibility, reproducibility, and impact. They demonstrate transparency and thoroughness—qualities valued by reviewers and readers alike.
Remember the key principles:
- Essential content stays in the main text; supplementary materials support, not replace
- Follow journal guidelines meticulously—format, size, and naming matter
- Document everything with a clear README
- Reference supplements in your manuscript so readers know they exist
- Consider data repositories for very large datasets
By mastering supplementary materials preparation, you not only improve your chances of publication but also contribute to the broader scientific ecosystem. Well-organized data and methods enable others to build on your work, accelerating discovery.
Need help organizing your research data or preparing supplements? Our team at QualityCustomEssays specializes in research data management, manuscript preparation, and journal submission support. From Data Management Plans to final supplementary file formatting, we ensure your submission meets the highest professional standards. Contact us for a free consultation →
Endnotes
- Elsevier. (2025). What are the requirements for my supplementary material? Elsevier Support. https://www.elsevier.support/publishing/answer/what-are-the-requirements-for-my-supplementary-material
- Springer Nature. (n.d.). Supplementary information. Nature for Authors. https://www.nature.com/nature/for-authors/supp-info
- Pop, M. (2015). Use and mis-use of supplementary material in science publications. PeerJ, 3, e1338. https://doi.org/10.7717/peerj.1338
- Enago Academy. (2017). Why you should submit supplementary material with your manuscript. https://www.enago.com/academy/submit-supplementary-materials-manuscript/
- Nature. (n.d.). Supplementary information. https://www.nature.com/nature/for-authors/supp-info
- Cambridge University Press. (n.d.). Authors publishing supplementary material. https://www.cambridge.org/core/services/authors/publishing-supplementary-material
- Pop, M. (2015). Use and mis-use of supplementary material in science publications. https://doi.org/10.7717/peerj.1338
- Taylor & Francis. (n.d.). Enhancing your article with supplementary material. https://authorservices.taylorandfrancis.com/publishing-your-research/writing-your-paper/enhancing-your-article-with-supplementary-material/
- Wiley. (n.d.). Supporting information. Author Resources. https://authors.wiley.com/author-resources/Journal-Authors/Prepare/manuscript-preparation-guidelines.html/supporting-information.html
- Springer Nature. (n.d.). Authors publishing supplementary material. https://www.cambridge.org/core/services/authors/publishing-supplementary-material
- IEEE Author Center. (n.d.). Prepare supplementary materials. https://journals.ieeeauthorcenter.ieee.org/create-your-ieee-journal-article/prepare-supplementary-materials/
- Harberson, S. (n.d.). What are supplementary materials — and why are they critical for scientific progress? Copyright.com blog. https://www.copyright.com/blog/what-are-supplementary-materials-and-why-are-they-critical-for-scientific-progress/
- Paperpal. (2023). Supplementary materials in research: 5 tips for authors. https://paperpal.com/blog/researcher-resources/phd-pointers/supplementary-materials-in-research-5-tips-for-authors
- IOP Publishing. (n.d.). Supplementary material and data in journal articles. Publishing Support. https://publishingsupport.iopscience.iop.org/questions/supplementary-material-and-data-in-journal-articles/
