March 27, 2026
You finished your term paper, exported it to PDF, and opened Moodle to submit -- only to see "file exceeds upload limit." The report is just 3MB, but the system only accepts 2MB. This is surprisingly common because many Moodle servers still run on default PHP settings that no one has changed.
This guide covers the PDF upload limits for the most common educational platforms and what to do when your file is too large.
Upload Limits by Platform
| Platform | Upload Limit | Notes |
|---|---|---|
| Moodle (self-hosted) | Default 2MB | PHP default; admin-configurable but often unchanged |
| MoodleCloud (hosted) | Hard cap 250MB, default 1MB | Admin can adjust up to 250MB |
| Canvas LMS | 5GB / file | Course storage quota defaults to 500MB; hard cap is fixed |
| Turnitin | 100MB, 800 pages max | PDF must contain selectable text (scanned images rejected) |
| Google Classroom | 5TB (via Google Drive) | LTI-integrated assignments: 10MB / file, max 20 attachments |
The most common bottleneck: Moodle defaults to just 2MB. This is the PHP upload_max_filesize default. Many school IT administrators have not adjusted it. If your school uses Moodle and you hit the 2MB limit, ask your instructor or IT department if they can raise it. In the meantime, compress your PDF to fit.
Moodle: Why Is the Limit So Small?
Moodle's upload limit is layered. The system uses the smallest value across all levels:
- PHP setting (upload_max_filesize) -- default 2MB
- PHP setting (post_max_size) -- default 8MB
- Moodle site-wide setting -- admin-configurable
- Course-level setting -- cannot exceed site setting
- Activity-level setting -- cannot exceed course setting
Even if your instructor sets 50MB at the assignment level, if PHP is still at the 2MB default, the effective limit is 2MB. Compression is the fastest solution when this happens.
Turnitin: Watch Out for "Unrecognized" Files
Turnitin has a unique requirement: PDF files must contain selectable text. If your PDF is a scanned image (you cannot highlight or select text when you open it), Turnitin will reject the submission outright.
How to handle this:
- If you export directly from Word, Google Docs, or LaTeX, you are fine -- these naturally produce PDFs with selectable text
- If you have scanned documents that need to go through Turnitin, you need OCR (Optical Character Recognition) software to add a text layer to the scanned images
- Another option is to retype the content into Word and export as PDF
Beyond the text requirement, Turnitin has a 100MB and 800-page limit. Regular papers and theses rarely hit these caps.
Google Classroom and Canvas
Google Classroom has very generous limits since files go through Google Drive, with a theoretical 5TB cap. PDF size is virtually never a concern. The only exception is LTI-integrated grading assignments, which cap at 10MB per file.
Canvas LMS allows up to 5GB per file, but each course has a default 500MB storage quota. If your semester's submissions add up to more than 500MB (possible with lots of images or large PDFs), your instructor may need to request a quota increase from IT.
University Thesis Submission Systems
University electronic thesis and dissertation (ETD) systems typically do not publicly display their file size limits. Based on our research, major universities require PDF format, but specific size limits are only visible after logging into the submission portal.
If you are preparing a thesis submission:
- Log into the system early to check the upload limit
- Ask the library or your department's administrative office
- Thesis PDFs with many figures can be large -- compress if needed, but be careful about figure clarity
Getting the Best PDF Quality Within Size Limits
Hitting a size limit does not mean quality has to suffer. The key is choosing the right DPI (resolution) so each page gets enough space to remain clear.
How DPI Affects File Size
For A4-sized pages, approximate file size per page:
| DPI | Color (per page) | Grayscale (per page) |
|---|---|---|
| 150 DPI | ~200-400KB | ~80-150KB |
| 200 DPI | ~400-800KB | ~150-300KB |
| 300 DPI | ~800KB-2MB | ~300-600KB |
Calculating Your Per-Page Budget
Target size / number of pages = per-page budget
Example: you need to fit a 20-page report into Moodle's 2MB limit. Set your target to 1.8MB (with buffer). Your per-page budget is 90KB. Looking at the table, 90KB is roughly 150 DPI grayscale -- perfectly adequate for a text-based report.
A 5-page report at 1.8MB gives each page 360KB, allowing 150-200 DPI color with good quality.
Recommendations by Assignment Type
- Text reports (essays, papers, theses): PDFs exported from Word or LaTeX are usually small enough. If they include many embedded images, compress at 200 DPI color
- Scanned assignments (handwritten work, paper submissions): These are most likely to exceed limits. Scan at 150 DPI grayscale from the start rather than scanning at high resolution and compressing later. If already scanned, use PDF Under's compress tool to set a target size
- Reports with many figures (lab reports, design work): 200 DPI color is usually the best balance. If space is tight, prioritize chart and text clarity over background image quality
- Presentation PDFs: PowerPoint exports tend to be large (each slide is a full-page image). Compressing to 150-200 DPI looks virtually identical on screen
Set your compression target to 90% of the limit. For Moodle's 2MB, target 1.8MB. For Canvas, keep in mind the cumulative storage quota across the entire semester.
Quick Action Checklist When You Hit a Limit
- Confirm the exact limit (check the error message or system settings)
- Use PDF Under's compress tool with a target at 90% of the limit
- If quality after compression is not good enough, use the split tool to extract only the required pages
- If Turnitin rejects your scanned PDF, run OCR processing first
- If the limit is unreasonably low, ask your instructor or IT department to raise it