Why did my file get bigger instead of smaller?

This can happen if the PDF is already highly compressed, if the chosen setting increases resolution (e.g., 300 dpi) or re-encodes images, if elements are added (OCR layer, fonts/resources), or if the output mode (e.g., PDF/A, linearization) adds structure and metadata. Tips: try a lower quality (72/150 dpi), avoid PDF/A if not necessary, and don’t enable OCR unless needed.

What is PDF/A? Why can it be heavier, and what happens when you compress it?

PDF/A is a PDF profile for long-term archiving (embedded fonts, standardized colors, rich metadata, no scripts/videos). It can be heavier than a regular PDF because it embeds more information. When compressing, the gain is often small or negative because mandatory elements can’t be removed and some re-encoding adds weight. Tip: if legal archiving isn’t required, convert to a regular PDF first, then compress (e.g., 150 dpi for balance, 72 dpi for the web).

Compress a PDF

Q: What size can I expect after compression?

Depending on the content (images, text, scans), a 10 MB PDF can drop below 1 MB with “low quality”, or around 2–3 MB with “medium quality”. Results vary with image density and original resolution.

Q: What is the average reduction rate?

In general, expect a reduction of 50% to 90%. The biggest gains come from image-heavy PDFs (scans, photos, presentations).

Q: Will the compressed file pass through email?

Yes. Email providers often limit attachments to 20–25 MB. If your PDF is still bigger, try a lower quality or split the document before sending.

Q: Will visual quality remain acceptable?

At 300 dpi (high quality), readability and logos remain crisp for light printing. 150 dpi is a good all-round screen option. 72 dpi targets minimal size for the web.

Q: Which setting should I choose for the web?

For fast online display or uploads, choose 72 dpi. For comfortable reading across devices, pick 150 dpi.

To compress a PDF online: upload your file, choose a compression level, then start optimization. You’ll get a lighter, readable PDF ready to send. Fast, free, no sign-up.

Steps (show)

Upload the PDF file.
Choose the compression level.
Click “Compress”.
The result downloads automatically.

Choose a file or drag it here
(PDF format only)

Compressing...

A simple, fast and secure tool to compress your PDFs

Difyzi’s PDF compression tool lets you reduce file size while keeping documents readable.
Choose the level that fits your needs: low, medium or high quality. Perfect for emailing, sharing online, or archiving.
No sign-up, and your files are automatically deleted from our servers after download.

Frequently asked questions

Depending on the content (images, text, scans), a 10 MB PDF can drop below 1 MB with “low quality”, or around 2–3 MB with “medium quality”. Results vary with image density and original resolution.

In general, expect a reduction of 50% to 90%. The biggest gains come from image-heavy PDFs (scans, photos, presentations).

Yes. Email providers often limit attachments to 20–25 MB. If your PDF is still bigger, try a lower quality or split the document before sending.

At 300 dpi (high quality), readability and logos remain crisp for light printing. 150 dpi is a good all-round screen option. 72 dpi targets minimal size for the web.

For fast online display or uploads, choose 72 dpi. For comfortable reading across devices, pick 150 dpi.

This can happen if:

The PDF is already highly compressed (few images, mostly text).
The chosen setting increases resolution or re-encodes images (e.g., switching to 300 dpi).
Elements are added (OCR layer, embedded fonts/resources).
The output mode (e.g., PDF/A, web linearization) adds structure/metadata.

Tip: try a lower quality (72/150 dpi), avoid PDF/A if not required, and don’t run OCR unless you need it.

PDF/A is a PDF profile for long-term archiving: embedded fonts, standardized colors, no scripts/videos, rich metadata…

Consequence: it can be heavier than a regular PDF because it embeds more information (fonts, ICC profiles, archival structure).

Compressing a PDF/A: the gain is often small or even negative (file size can increase) because mandatory elements can’t be removed and some re-encoding adds weight.

Tip: if legal archiving isn’t needed, convert to a “regular” PDF first, then compress (e.g., 150 dpi for balance, 72 dpi for the web).