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How to compress a PDF

In short

Drop the PDF onto Compress PDF, choose Basic, Recommended or Strong, and check the before and after size. Compression works by shrinking oversized images, so scans and photo-heavy files get much smaller while a file that is all text barely changes. Your original file is left as it was.

Almost every oversized PDF is oversized for one reason: the images inside it are stored at far higher resolution than anything needs. Compression works by fixing that, which is why it helps enormously on some files and not at all on others.

Open Compress PDFShrink heavy files, keep the text sharp

Step by step

  1. Upload the file

    Drop your PDF onto Compress PDF. Files up to 50 MB are accepted.

  2. Choose how hard to compress

    Basic keeps the most detail. Recommended is the balanced setting most documents want. Strong produces the smallest file and is the one to pick when a size cap matters more than image fidelity.

  3. Check the saving before you keep it

    After it runs you are shown the before and after size and the percentage saved, so you can judge whether the trade was worth it. Your original is untouched either way.

Text stays sharp: only images are resampled

Text in a PDF is stored as vector instructions, not pixels, so compressing does not blur it. It prints at full sharpness at any size. What changes is the resolution of embedded photos and scans.

When compression will not help

A text-only PDF is already close to its minimum size, and compressing it can even make it slightly larger, because the file structure gets rewritten. If you see that result, keep your original. It is the better copy. Files that are large because they have hundreds of pages need Split PDF, not compression.

Common questions

How much smaller will my PDF get?

It depends entirely on what is inside. Scans and photo-heavy documents usually shrink the most, often to a fraction of their size, while a document that is only text may barely shrink at all. The result screen shows the exact size before and after, so you always see what you got.

Will compressing make my PDF blurry?

Text will not change. Photographs and scans are resampled, so at Strong compression a heavily enlarged image will show the difference.

Is the original file changed?

No. Compression produces a new file and leaves the original on your device exactly as it was.

Why this happens, and when to do something else

  • Why is my PDF so large?PDF size depends on the objects stored inside it, not just its page count. Large scans, repeated images, embedded fonts and retained revisions can dominate the bytes. Identify the likely payload before reducing quality or rearranging pages.
  • Why won't my PDF attach to an email?Check whether the failure happens while attaching, while sending or after delivery is rejected. Email encoding increases the data carried by binary attachments, and the recipient can impose a different limit from the sender. Measure the complete attachment set before choosing a smaller copy or an accepted alternative.
  • Compress PDF or reduce page count: which do I need?Use compression for a file-size problem, page repacking for suitable sparse document layout, and printer settings for paper use. These operations change different quantities. Measure the output that matters instead of treating fewer pages, fewer bytes and fewer sheets as interchangeable.
  • How to get a PDF under 100 KB without making it unreadableTreat 100 KB as a measured byte limit, not a quality setting. Aim below 100,000 bytes when the receiver’s interpretation is unclear, then inspect the actual output. Some complete PDFs cannot fit that small without unacceptable loss, so keep the original and confirm an accepted alternative when needed.

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