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Compress PDF File

Reduce the file size of your PDF by optimizing embedded images and cleaning metadata while keeping text, links, and forms intact.

Optimizes embedded images and cleans metadata while keeping text, links, and forms intact. Choose compression presets from aggressive to high quality.
Privacy Note: PDFs are uploaded to our servers for processing and immediately returned - they are not stored. Files are processed entirely in memory and deleted immediately after compression completes.
Drop PDF file here or click to browse
Select a PDF file to compress (max 100MB)

How to compress PDF files and make them smaller

PDF files grow large because they bundle text, vector graphics, fonts, and embedded images into a single container. The images are the biggest culprit. When you compress a PDF, the tool re-encodes those embedded images at a lower quality or a reduced resolution, then strips redundant metadata and rebuilds the internal file structure. The result is a smaller file that still opens and prints correctly.

SimpleSize handles this in the browser without an account. Upload your file, pick a preset, and download the result. Files are processed server-side and returned directly, so nothing is stored after your session ends.

Three compression presets and what they actually do

The tool offers three presets that control how aggressively embedded images are re-encoded. Choosing the right one depends on how the PDF will be used.

  • Aggressive (screen): Targets screen viewing. Images are downscaled to 96 DPI and compressed at a lower quality setting. Produces the smallest file, but fine print details may soften. Good for email attachments and sharing links.
  • Balanced (ebook): The default. Images are reduced to 150 DPI with a moderate quality setting. Suitable for most documents, including reports, invoices, and ebooks. Balances file size against visual fidelity.
  • High quality (printer): Targets print output. Images are retained at up to 300 DPI. The file shrinks less, but text and photo detail stay sharp enough for physical printing.

Beyond the preset, you can override two individual settings. "Image Quality" (50 to 95) sets the JPEG compression level for embedded images. "Max DPI" (96, 150, 200, or 300) caps the resolution of any image inside the PDF. These two controls let you fine-tune results when the preset alone is not enough.

Step-by-step: Reducing a PDF's file size

  1. Open the compress PDF tool on SimpleSize.
  2. Drag your PDF onto the dropzone, or click to browse your device. Files up to 100 MB are accepted.
  3. Select a preset. "Balanced (ebook)" is the default and works well for most documents.
  4. Optionally set a custom Image Quality value and a Max DPI cap if you need more control.
  5. Click "Compress PDF" and wait for processing to finish.
  6. Review the results panel, which shows the original size, the compressed size, the savings percentage, and the page count.
  7. Click the download button to save the smaller file to your device.

If the tool determines that the PDF is already fully optimized, it returns the original file unchanged and labels the result "passthrough (already optimized)" with 0% savings. This happens when the internal structure cannot be reduced further without data loss beyond the chosen preset's threshold.

When to shrink a PDF and when not to

Not every PDF benefits equally from compression. Understanding the file's content helps you set expectations.

  • Scanned documents: These are almost entirely images. Compression typically cuts file size significantly, sometimes by 60 to 80 percent, because the embedded JPEGs or TIFFs re-encode well.
  • Text-only PDFs: Files that contain only fonts and vector text have very little image data to compress. Savings are usually small, often just a few percent from metadata cleanup.
  • Mixed documents (reports, presentations): Results vary by how many high-resolution images are embedded. The Balanced preset is a good starting point.
  • Digitally signed PDFs: Compression can invalidate digital signatures because it modifies the file structure. If signature validity matters, keep a signed copy before compressing.
  • Print-ready artwork: Use the "High quality (printer)" preset to avoid visible degradation in photos or color-critical graphics.

For a deeper look at how PDF compression works across different document types, the PDF compression guide on the SimpleSize blog covers the mechanics in more detail.

How this tool differs from other ways to reduce PDF size online

Many browser-based PDF tools rely on a single compression pass with no user control. SimpleSize gives you three presets plus two independent overrides, which means you can match the output quality to the actual use case rather than accepting a one-size-fits-all result.

  • No account or login required. The tool works immediately without registration.
  • The 100 MB file size limit covers most real-world documents, including large scanned reports.
  • If the compressed file would be larger than the original (which can happen with already-optimized PDFs), the tool returns the original automatically. You never receive a file that is bigger than what you uploaded.
  • The fallback pipeline means the tool tries multiple strategies before giving up, including a metadata-strip-and-rebuild pass when the primary compression method does not produce a smaller result.
  • Results include exact byte counts and a savings percentage, so you can see precisely what changed.

If you also need to shrink images before embedding them in a document, the image compression tool handles JPEG, PNG, WebP, and other formats separately.

FAQ

The tool re-encodes embedded images at a lower JPEG quality and downscales them to a maximum DPI you control. It also strips metadata, removes redundant internal objects, and rebuilds the PDF's cross-reference table. Text and vector layers are not touched, so readable content stays sharp. The compression engine maps each preset to a specific quality profile that targets screen, ebook, or print output.

Yes. Compressing a PDF on SimpleSize is free with no account required. You can upload a file, choose a preset, adjust optional settings, and download the result without signing up or paying anything. There are no watermarks added to the output file.

"Balanced (ebook)" is the default and suits most documents, including reports, invoices, and presentations. Choose "Aggressive (screen)" when file size matters most and the PDF will only be viewed on a screen, such as an email attachment. Choose "High quality (printer)" when the file will be printed and image sharpness is important. You can also fine-tune with the Image Quality and Max DPI overrides after picking a preset.

This happens when the PDF is already optimized at or below the quality level the chosen preset targets. The tool runs a full compression pipeline, and if every method produces a file larger than the original, it returns the original unchanged and labels it "passthrough (already optimized)". PDFs that contain only text, or that were previously compressed, most commonly hit this case. Trying a more aggressive preset may produce small savings.

The tool accepts PDF files up to 100 MB. Files above that limit are rejected before processing begins. If your file exceeds 100 MB, consider splitting it into smaller sections using a PDF editor before uploading, or use the "Aggressive (screen)" preset on a smaller subset of pages first.

Files are processed server-side and returned directly in the same request. They are not stored on the server after processing completes. No account is created and no file history is retained. For full details on data handling, see the privacy policy .

No. The compression process targets embedded raster images only. Text stored as actual characters and vector elements such as lines, shapes, and fonts are not re-encoded or downsampled. A PDF with selectable, searchable text will remain fully searchable after compression. If your PDF consists of scanned page images rather than real text, the image quality settings will affect how legible those scans appear after downscaling.

The tool validates the file structure before and after processing. It checks for a valid PDF header, an end-of-file marker, and internal cross-reference structures. If the file fails validation, it is rejected with an error message indicating the file appears incomplete or corrupted. Partially downloaded or truncated PDFs are the most common cause of this error.

Compressing an image file (JPEG, PNG, WebP) re-encodes the entire file as a single raster object. Compressing a PDF is more complex because a PDF is a container that holds multiple objects: fonts, vector paths, metadata, and one or more embedded images. A PDF compressor must parse the container, locate the image streams inside it, re-encode each one, then rebuild the container structure around them. The image compression tool handles standalone image files separately if you need to shrink those before embedding them.

Yes. Most email providers cap attachments at 10 to 25 MB. Using the "Aggressive (screen)" preset with a low Max DPI setting (96 or 150) gives the largest size reduction and is well suited for documents that will only be read on screen. If the file is still too large after compression, splitting the PDF into smaller parts is the next option. The SimpleSize blog covers common email attachment limits in detail.

Yes, it can. Digital signatures in PDFs work by storing a cryptographic hash of the file's byte content at the time of signing. Any modification to the file structure, including image re-encoding or metadata removal, changes that byte content and breaks the signature's validity check. If you need to share a signed PDF and also reduce its size, keep the signed original and share the compressed version only where signature verification is not required.

"Image Quality" sets the JPEG compression level applied to raster images inside the PDF, on a scale from 50 (most compressed, lower fidelity) to 95 (least compressed, higher fidelity). "Max DPI" caps the pixel density of embedded images. An image originally at 600 DPI with a Max DPI of 150 will be downscaled to 150 DPI, reducing its pixel count and therefore its contribution to file size. Both settings override the defaults set by the chosen preset.