PDF Compressor Online
Reduce PDF file size using simple quality and resolution controls. Set an optional target size, review the result, and download the compressed document. All processing happens locally in your browser.
Choose a PDF to Compress
Drop one PDF here or choose a file from your device.
PDF document · One file at a timePractical Note: Large or image-heavy PDFs may take longer to process. Compression runs locally; files are not uploaded to servers.
What Is a PDF Compressor?
A PDF compressor reduces the file size of a PDF. A smaller file is easier to email, upload, store, and share.
PDFs can contain scanned pages, photographs, text, fonts, links, forms, metadata, and graphics. The amount of reduction depends on the file and how it was created.
Scanned and image-heavy PDFs usually have more room for compression. A small text-based PDF may already be optimized and may show little change.
Start with Recommended, Smaller File, Maximum Compression, or use custom settings.
Adjust page quality, resolution, color mode, and supported metadata removal.
Compare the original size and compressed size before downloading the result.
How to Compress a PDF
- Choose a PDF. Select one PDF file from your device.
- Select a preset. Start with Recommended for a balance between readability and size.
- Adjust the settings. Change the image quality, resolution, grayscale, or metadata option when needed.
- Compress the PDF. Wait while the pages are processed and added to a new PDF.
- Check the result. Compare the original and compressed sizes.
- Download and open the file. Make sure every important page is readable before using it.
How This PDF Compressor Works
The tool opens each page and turns it into a page image. It then reduces the image quality or resolution based on your settings and places the processed pages into a new PDF.
This method works well for scanned documents and photo-heavy PDFs because those files already contain large images.
The new PDF keeps the visible page design, but it may not keep the original document structure. Text may remain visible but may no longer be selectable, searchable, or editable.
Which PDFs Compress Best?
| PDF Type | What It Contains | Expected Result |
|---|---|---|
| Scanned PDF | An image of each scanned page | Often has more room for compression |
| Photo-heavy PDF | Large photographs and detailed images | May shrink when images are resized and compressed |
| Text-based PDF | Selectable text, fonts, and page instructions | May already be small and show little reduction |
| Vector PDF | Lines, diagrams, shapes, and scalable graphics | Turning pages into images may reduce sharpness |
| Previously compressed PDF | Images that have already been reduced | May show little further reduction |
Choosing the Right Settings
Start with the Recommended preset. Use stronger settings only when the file is still too large.
| Document Type | Suggested Starting Point | What to Check |
|---|---|---|
| Scanned form | Recommended preset and original color | Names, numbers, signatures, and stamps |
| Certificate | Recommended preset with medium resolution | Small text, seals, and signatures |
| Black-and-white notes | Balanced quality with grayscale | Handwriting and light marks |
| Photo document | Balanced quality and original color | Faces, photographs, and color details |
| Searchable text PDF | Keep the original when text selection is required | Text, links, forms, and signatures |
Image Quality and File Size
Image quality controls how much page detail is kept in the compressed PDF.
- Higher quality keeps text and images clearer but normally creates a larger file.
- Balanced quality reduces the size while trying to keep normal text readable.
- Lower quality creates a smaller file but may add blur or visible compression marks.
Check small text, dates, numbers, signatures, QR codes, stamps, and fine lines after compression.
Resolution and DPI
Resolution controls how many pixels are used to rebuild each page. The interface may show this setting as DPI.
A lower resolution usually creates a smaller file. It can also make small text and detailed images less clear.
- 300 DPI keeps more detail but usually creates a larger file.
- 150 DPI is a practical starting point for many screen-viewed documents.
- 96 or 72 DPI creates a smaller file but may reduce readability.
When to Use Grayscale
Grayscale removes color and keeps shades between black and white. It can help reduce the size of scanned forms, notes, letters, and documents that do not need color.
Keep the original color when it contains important information. Examples include photographs, colored charts, maps, highlighted text, stamps, and identity documents.
What Strong Compression May Remove
Because each page may be rebuilt as an image, the compressed PDF may no longer contain:
- Selectable or searchable text
- Clickable website and email links
- Fillable form fields
- Digital signatures and signature checks
- Bookmarks and document outlines
- Embedded attachments and layers
- Vector graphics at their original quality
- Screen-reader tags and document structure
Do not use strong compression when the destination requires searchable text, a working form, or a valid digital signature.
Why a PDF May Not Become Much Smaller
A PDF may show little reduction when its images are already compressed, it contains mostly efficient text and graphics, or the selected settings are close to the original quality.
Removing metadata normally saves only a small amount of space. Most file-size reduction comes from lowering page-image quality or resolution.
Why a Compressed PDF Can Be Larger
A small text-based PDF can become larger when its efficient text and page instructions are replaced with full-page images.
When this happens, keep the original file or try a lower image quality and resolution.
Common PDF Compression Mistakes
- Not opening the result: check every page before uploading or sharing the PDF.
- Deleting the original: keep the source file in case you need better quality or selectable text.
- Starting with maximum compression: begin with Recommended and reduce quality only when necessary.
- Compressing the result again: repeated compression can make text and graphics progressively worse.
- Ignoring forms and signatures: strong compression may remove or invalidate them.
- Using grayscale without checking: important color details may be lost.
Browser Memory and Large PDFs
PDF compression can use a large amount of browser memory because every page must be opened, processed, and added to a new document.
Large page sizes, many pages, and high-resolution scans require more memory. Processing may therefore be slower on phones and older computers.
When processing fails, try closing other browser tabs, lowering the resolution, splitting the PDF, or using a device with more available memory.
Browser Processing and File Data
PDF processing is designed to run in the browser. PDF contents, page previews, filenames, passwords, metadata values, and downloaded documents should not be included in analytics events.
The page may still load normal website resources and analytics. Browser-based file processing does not mean the complete page works without network activity.
Related PDF Tools
Frequently Asked Questions
How do I compress a PDF?
Choose a PDF, select a compression preset, adjust the quality or resolution when needed, and click Compress PDF. Open the downloaded result and check every important page.
Which PDF files compress the most?
Scanned and image-heavy PDFs normally have more room for reduction. Text-based and previously optimized PDFs may show little change.
How does this PDF compressor work?
The tool turns each PDF page into an image, reduces the page-image quality or resolution, and places the processed pages into a new PDF.
What is the difference between a scanned PDF and a text PDF?
A scanned PDF usually contains an image of each page. A text PDF stores selectable text, fonts, and page instructions.
Does this compressor keep selectable text?
Strong compression may turn every page into an image. Text can remain visible but may no longer be selectable or searchable.
Are links, forms, and bookmarks preserved?
Rebuilding pages as images normally removes clickable links, form fields, bookmarks, and similar interactive features.
Will a digital signature remain valid?
Changing or rebuilding a signed PDF can remove or invalidate its digital signature. Keep the original signed document.
What does the image-quality setting change?
Higher quality keeps more page detail and normally creates a larger file. Lower quality creates a smaller file but may reduce clarity.
What does DPI mean in this tool?
DPI represents the approximate resolution used when each page is rebuilt. Lower values use fewer pixels and generally create a smaller file.
Does grayscale reduce PDF size?
It may reduce the size of color scans and image-heavy PDFs. Keep the original color when it contains important information.
Why is the compressed PDF blurry?
The selected image quality or resolution may be too low. Try the Recommended preset or increase both settings.
Why is the compressed PDF larger than the original?
A small text or vector PDF can become larger when its pages are converted into full-page images.
Can supported metadata be removed?
When enabled, the tool can remove supported fields such as title, author, subject, keywords, creator, and producer.
Can a password-protected PDF be compressed?
A protected PDF may need to be unlocked first. Only remove a password when you own the document or have permission.
Does the PDF compressor work on mobile?
It can work in supported mobile browsers, but large or high-resolution PDFs may require more memory than a phone has available.
Are PDF contents sent to analytics?
PDF contents, page previews, filenames, passwords, metadata values, and downloaded documents should not be included in analytics events.
Why did PDF compression fail?
The PDF may be damaged, password protected, unsupported, or too large for the available browser memory.
