How to reduce PDF size for forms, email and school uploads
“File too large” is one of the most common upload errors. Job portals, government forms and school systems like Canvas or Google Classroom often set a size limit, and email services refuse attachments above a certain size. The good news: most PDFs can be made much smaller in under a minute.
Why is my PDF so big?
A PDF is usually large for one of three reasons:
- It is made from photos or scans. Every page is a big, high-resolution picture. A 10-page phone scan can easily be 20MB.
- It contains large images. Brochures and reports with full-page photos carry a lot of image data.
- It was saved without compression. Some apps save the PDF in a very wasteful way.
Text-only PDFs are already small (often under 200KB), so they rarely need shrinking.
How to make a PDF smaller, step by step
- Open our Make PDF smaller tool.
- Tap the pink box and choose your PDF.
- Pick the size you need: 100KB, 200KB, 500KB, 1MB, 2MB, 5MB, 10MB, 25MB or your own number. If you have no limit, choose “Smaller”.
- For scanned homework or documents, tick “Black & white” — it gives the smallest file and the clearest text.
- Press the big button, check the preview and the new size, then download.
Tip: the tool tries the clearest setting first and only goes smaller if it must, so you get the best quality that still fits your limit.
Common size limits
Limits change and can differ between organisations, so always check the instructions on the page you are uploading to. These are typical numbers:
| Where you are sending it | Typical limit |
|---|---|
| Gmail, Yahoo Mail (sending) | 25MB |
| Outlook.com, iCloud Mail (sending) | 20MB |
| Job portals and government application forms | Often 100KB to 2MB per document |
| School and university upload systems | Varies — often 5MB to 10MB per file, set by your school |
If your email provider is not listed, aim to keep attachments under 20MB to be safe.
Will compression make my PDF blurry?
A little, if you go very small. A 1–2 page document at 100–200KB is usually perfectly readable. A 20-page scan squeezed to 100KB will look soft. If the text becomes hard to read:
- Choose a bigger size limit if the form allows it.
- Use Black & white — it keeps writing sharp at small sizes.
- Remove pages you don’t need with Turn, reorder & delete pages, or split a long file with Split a PDF.
Good to know: when a PDF is squeezed to a set size, each page is saved as a picture, so you can no longer select or copy the text. Keep your original file if you need to edit it later.
Start with a smaller file next time
- When scanning with your phone, use our Photos to PDF tool and pick “Under 5MB” or “Under 2MB” before you create the PDF.
- Exporting from Word or Google Docs? Choose “Save as PDF” rather than “Print to PDF” — it usually creates a smaller file.
Is it safe to compress private documents?
With DocAura, yes: your PDF is processed inside your own browser and is never uploaded to any server. You can even switch on airplane mode after the page loads and it still works.