How to Compress a PDF Without Losing Quality
Hit an email or upload size limit? Here is how to shrink a PDF, what really makes it big, and which setting to pick.
PDFixed Team
4 min read
Key takeaways
- Most of a PDF's size comes from photos and scans, not from text.
- Start with the Recommended level; only use Strong compression if the file is still too big.
- A PDF that is mostly text may only get a little smaller, and that is normal.
- Compressing in your browser means your document never has to be uploaded.
To compress a PDF, open PDFixed's Compress PDF tool, choose a level and download the smaller file. Start with the Recommended level, and it runs in your browser, so your document is not uploaded.
You attach a PDF to an email and get a message saying it is too large. Or a job application portal only accepts files under 5 MB. Compressing the PDF is the quick fix, and it usually takes less than a minute.
This guide explains why PDFs get so big, how to shrink one for free, and how to choose the right level so the document still looks good.
Why are some PDFs so big?
Text takes almost no space. A 50-page report with only words can be smaller than 200 KB. What makes a PDF heavy is almost always images:
- Scans. A scanned page is a full-size picture. A scanned 20-page contract can easily be 30 MB or more.
- Photos. Brochures, catalogues and presentations exported at print quality carry huge pictures.
- Pictures bigger than they need to be. A photo shown at the size of a stamp may still be saved at full camera resolution.
Because images cause the problem, that is also where compression helps.
How do I compress a PDF online for free?
- Open Compress PDF.
- Click Select PDF file, or drop your PDF onto the page.
- Choose a compression level (see the next section).
- Click Compress PDF.
- Check the before-and-after size, then click Download PDF.
Compression happens in your browser, so your document is not uploaded anywhere. You can read more about why that matters in Are online PDF tools safe?
Which compression level should I choose?
| Level | Best for | What to expect |
|---|---|---|
| Light compression | Documents that will be printed or read closely | Best quality, smaller saving |
| Recommended | Email, uploads and everyday sharing | Good quality, good saving |
| Strong compression | Hitting a strict size limit | Smallest file, lower image quality |
Start with Recommended. If the file is still too big, go back and try Strong compression. You can always compress the original again, so there is no harm in testing.
Why did my PDF only get a little smaller?
If a PDF is mostly text, there is not much to shrink. Compression works on the pictures inside the file, so a text-only contract might drop by a few percent, while a scan or a photo-heavy brochure can lose more than half its size.
PDFixed also never returns a file that is bigger than the one you started with. When it cannot make your PDF smaller without losing quality, it says so and you can keep your original.
Other ways to make a PDF smaller
If compression alone is not enough, try these:
- Remove pages you do not need. Fewer pages means a smaller file. See How to remove pages from a PDF.
- Split the PDF. Two files of 8 MB can each be sent, even if the full 16 MB cannot. See How to split a PDF.
- Scan at a lower resolution. For plain text documents, 200 DPI black-and-white is usually enough, and far smaller than a 600 DPI colour scan.
- Export again from the source. If you still have the Word or design file, exporting with a "minimum size" or "web" option often beats compressing afterwards.
How do I compress a PDF on Mac?
Preview can reduce the size without extra software:
- Open the PDF in Preview.
- Choose File → Export.
- Open the Quartz Filter menu and pick Reduce File Size.
- Save the new file.
This filter can be heavy-handed and make images blurry, so check the result. If it looks too soft, use a compression tool where you can choose a lighter level.
How do I compress a PDF on Windows or a phone?
Windows has no built-in PDF compressor. The simplest option is to use a browser tool. PDFixed Compress PDF works the same way in Chrome, Edge, Safari and Firefox, on a computer, tablet or phone, and there is nothing to install.
What if the PDF is still too large?
Some files are simply big, such as a long scan with many colour photos. When no setting gets you under a limit, our experts can rebuild the document properly, for example by cleaning up the scans and replacing oversized images. Ask for a quote and we will tell you the price before any work starts.
Frequently asked questions
Can I compress a PDF for free?
Yes. PDFixed Compress PDF is free, with no sign-up and no watermark on your file.
Will compressing a PDF make it look worse?
Only the photos and scanned images inside it are re-saved at a smaller size, so they can lose a little sharpness. Text and drawings stay sharp and selectable. Light compression keeps the most quality.
Why did my PDF barely get smaller?
A PDF made mostly of text has very little to shrink. Compression works on the images inside it, so a text-only contract might only drop a few percent, while a scan or a brochure full of photos can shrink a lot.
What happens if the file cannot be made smaller?
PDFixed never gives you a bigger file. If it cannot make the PDF smaller without hurting quality, it tells you and lets you keep your original.
Is there a size limit?
You can compress PDFs up to 200 MB. Very large files may take a little longer on older phones and computers.
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