Make a PDF easier to send.
Optimize PDF streams and images, then download a smaller copy when there is space to save.
Start for freeCompress PDF, shown as a simplified diagram
Compressing a PDF optimizes its internal streams and images to reduce file size where possible, so the file is easier to email, upload, or store, though the amount of reduction depends on the file itself.
Why PDFs get too large to send
Scanned pages, embedded photos, and layers of document structure all add up. A PDF that started as a few pages of text can end up too large for an email attachment or an upload limit, especially once images are involved.
PDF Hammer’s compression tool optimizes what it safely can inside the file, then reports the actual result once it has finished.
How it works
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01
Add your PDF
Upload the file you want to shrink.
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02
PDF Hammer optimizes streams and images
Internal PDF streams are optimized, the document structure is streamlined, and embedded images are optimized for size.
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03
Review the measured result
PDF Hammer reports the actual size before and after processing, so you can see what changed for that specific file.
What this tool preserves and changes
What compression does
- Optimizes internal PDF streams and document structure.
- Optimizes embedded images to reduce their contribution to file size.
- Reports the measured size difference after processing, for the file you actually uploaded.
What compression does not promise
- It does not guarantee a fixed percentage reduction. Results vary by file.
- It is not lossless. Image optimization can change image quality.
- Already optimized or mostly-text files may see little or no safe reduction.
Processed in your browser
Compression runs locally in your browser for this tool. Your file is not uploaded to a server to shrink it.
Frequently asked questions
Will compression always make my file smaller?
Not always. Files that are already well optimized, or that are mostly text with few images, may see little or no safe reduction. PDF Hammer reports the measured result for your specific file rather than a promised percentage.
Does compression reduce image quality?
It can. Image optimization is one of the ways size is reduced, and depending on the setting used, that can change image quality. This is not a lossless process.
Is compression guaranteed to be a fixed percentage smaller?
No. The example figures shown on this page are illustrative only. The actual reduction depends on what is inside your specific file.
Is my file uploaded to compress it?
No, for this tool the optimization runs in your browser.