Why is my PDF so big?
A PDF’s weight rarely comes from its text. A page of text weighs only a few kilobytes. What makes a PDF heavy is almost always images: scanned pages, photos, screenshots or high-resolution graphics placed in the document.
Scanners and phone scanning apps often save each page as a large, barely compressed picture. A ten-page scan can easily reach 20 or 30 MB. Documents exported from design or office software can also carry images at print resolution, even when they will only ever be read on a screen.
A PDF can also contain leftovers: objects that are no longer used, duplicated resources, and metadata such as the author name and editing software. None of this is visible, but all of it adds weight.
How to reduce PDF size without losing quality
Plume works on what really makes the file heavy:
- It recompresses the images inside the PDF as JPG, at the quality and resolution of the preset you choose.
- It removes unused objects and metadata that serve no purpose.
- It rewrites the file with compressed object streams, a more compact way of storing the PDF structure.
Three presets cover most needs:
- High quality: images stay sharp, for documents you may print.
- Balanced: comfortable reading on screen, much lighter. The right choice for most files.
- Smallest: lower resolution, for strict upload limits.
The text is not turned into an image. It stays selectable and searchable, and links and pages are kept.
How much smaller will my PDF get?
To be honest, it depends on what the PDF contains.
- Scans and PDFs full of photos shrink a lot, often by 50 to 90%. This is where compression really helps.
- Mixed documents, such as a report with a few pictures, usually shrink by a noticeable but smaller amount.
- PDFs that are mostly text are already small. Plume can tidy them up a little, but do not expect a big difference.
Plume shows the size before and after for each file, so you know immediately whether it was worth it. If a text-only PDF is still too heavy, the cause is often an embedded font or a single large image.
Compress a PDF for e-mail or an online form
Sending by e-mail
Gmail accepts attachments up to 25 MB and Outlook up to 20 MB. Beyond that, your message bounces or the file is turned into a download link. A compressed PDF goes through as a normal attachment, and opens faster for the person receiving it.
Uploading to a portal
Administrative websites, banks, insurance companies and job platforms often cap uploads at 2 to 5 MB per document. Try Balanced first, then Smallest if the file is still too big. For scanned identity papers or payslips, Smallest usually stays perfectly readable.
If your document is still in Word or PowerPoint format, you can also compress the Word file or the presentation before exporting it.
Is it safe to compress a PDF online?
PDFs are often the most sensitive files we have: contracts, tax returns, medical results, ID scans, bank statements. Unlike most online tools that upload your files to their servers, Plume compresses the PDF inside your browser. The file never leaves your device. No copy is stored anywhere, and there is nothing to delete afterwards.
Once the page has loaded, it even works offline. You can compress several PDFs at once, with no account, no watermark and no daily limit. Very large files depend on your device’s memory: a few hundred MB is fine on a recent computer, while phones prefer smaller files.
Plume does not open password-protected PDFs.