PDF Compressor
Reduce your PDF file size instantly in your browser – no uploads, no server, 100% private.
Drag & drop your PDF here
Max 100 MB · Processed locally, never uploaded
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Compression Level
What Does This PDF Compressor Do?
This tool shrinks the file size of a PDF so it is easier to email, upload, or store. Drop in a PDF, pick a compression level, and it rebuilds the document at a smaller size by redrawing each page and re-encoding it as a compressed image before saving it back into a new PDF. Everything runs directly in your browser using pdf.js and pdf-lib, so the file never leaves your device and nothing is uploaded to a server.
How to Use This PDF Compressor?
- Upload your PDF. Drag and drop a file onto the drop zone, or click Choose PDF to browse for one on your device. Files up to 100 MB are supported.
- Check the file details. The file name and original size appear in a badge above the compression settings, so you can confirm it is the right document.
- Pick a compression level. Choose Low, Medium, or High depending on whether you want to keep more detail or get the smallest possible file.
- Click Compress PDF. A progress bar tracks the process page by page and updates as the file is rebuilt.
- Review the results. Once finished, a summary shows the original size, the new compressed size, and the percentage saved.
- Download the compressed file. Click Download to save the new PDF, or use Reset to start over with a different file.
Built-In Features
Drag and Drop Upload
Drop a PDF straight onto the upload area or browse for one manually. The file name and size are shown before compression starts.
Three Compression Levels
Choose Low for high quality, Medium for a balance of size and clarity, or High for the smallest possible file.
Instant Size Comparison
After compression, a summary card shows the original size, the compressed size, and the percentage saved.
Clear Error Messages
Password-protected files, corrupted PDFs, and unsupported files are each detected and explained in plain language, along with specific guidance if your device runs low on memory on a large file.
Handles Files Up to 100 MB
Upload PDFs up to 100 MB, well above the 10 to 25 MB cap many free online compressors enforce. Larger files get a heads-up about longer processing time before you commit.
Browser-Based, No Sign-Up
Your PDF is read and processed locally in your browser. Nothing is uploaded to a server, and no account is required.
Can You Compress a PDF Without Losing Quality?
Not entirely, and any tool that claims otherwise is oversimplifying. This tool reduces file size by re-encoding each page as a compressed image, which is a lossy method, meaning some detail is traded away for a smaller file. Other tools that promise “no quality loss” usually mean the loss is small enough to be invisible on screen, not that no data was removed. Choosing Low compression here has the same effect, keeping the reduction light enough that the difference is hard to notice at normal viewing size.
How PDF Compression Works
Most of the space in a PDF comes from the images and page graphics it contains. To shrink the file, this tool redraws every page at a chosen resolution and saves it as a compressed JPEG image, then places that image into a brand new PDF at the original page size.
Page Rendering
Each page is drawn onto a canvas at a set scale, then exported as a JPEG at a chosen quality level. Higher scale and quality keep more detail; lower settings produce a smaller file.
Rebuilding the PDF
Each compressed page image is placed into a new PDF at the same width and height as the original page, then the finished document is assembled and made ready to download.
Because every page is turned into an image during compression, any text in the original PDF will no longer be selectable or searchable in the compressed copy. Keep your original file if you need to copy text, search inside the document, or edit it later.
Which Compression Level Should You Choose?
Each level balances file size against visual quality differently. There is no single right answer, it depends on what you plan to do with the file afterward.
| Level | Typical Size Reduction | Best Suited For |
|---|---|---|
| Low | Around 10 to 25 percent | Photo-heavy documents, portfolios, and files you plan to print |
| Medium | Around 25 to 55 percent | General sharing, email attachments, and everyday documents |
| High | Around 55 to 80 percent | Archiving, upload size limits, and quick web sharing |
If a file is already well optimised, the tool will let you know that it could not be compressed further rather than producing a larger or identical file.
My PDF Is Too Large to Email, Now What?
Most email providers reject attachments past a set limit, usually around 20 to 25 MB. Compressing the file before attaching it is the fastest way around this without switching to a file-sharing link. Gmail caps total message size, including attachments, at 25 MB, while Outlook is typically stricter, around 20 MB. Since attachments are re-encoded for transfer, a file close to the limit can still bounce, so aim comfortably under it rather than right at it.
Common Reasons to Compress a PDF
Staying Under Email Limits
Many email providers cap attachments at around 25 MB. Compressing a large PDF first can be the difference between a message sending or bouncing back.
Faster Uploads
Job applications, form submissions, and cloud portals often reject or slow down on oversized files. A smaller PDF uploads faster and more reliably.
Saving Storage Space
Archiving years of scanned reports or invoices adds up quickly. Compressing them first keeps your drive or cloud storage from filling up as fast.
Quicker Sharing on Chat Apps
Smaller files send and download faster over messaging apps and slower mobile connections, which matters when sharing documents on the go.
Useful Tips
Start With Medium
If you are not sure which level to pick, try Medium first and check the results. You can always run the original file again at a different level.
Keep the Original for Text
Since compression turns pages into images, keep the original file on hand if you still need to select, copy, or search the text later.
Combining Files Afterward
If you need to compress several PDFs and then bring them together into one document, our Merge PDF tool can combine them once each one is compressed.
Need Individual Page Images?
If your goal is separate image files rather than a smaller PDF, our PDF to JPG Converter turns each page into its own downloadable image.
Frequently Asked Questions
How do I compress a PDF online for free?
Upload your PDF using the drop zone or Choose PDF button, pick a compression level, then click Compress PDF. Once processing finishes, download the smaller file directly. No account or payment is needed.
Does compressing a PDF reduce its quality?
Yes, to some degree. Every page is redrawn as a compressed image, so higher compression levels trade off more visual detail for a smaller file. Low compression keeps quality closer to the original.
Will the text in my PDF still be selectable after compression?
No. Compression rebuilds each page as a JPEG image inside a new PDF, so text can no longer be selected, copied, or searched. Keep the original file if you need those features.
What is the difference between Low, Medium, and High compression?
Each level renders pages at a different resolution and JPEG quality. Low keeps the most detail with the smallest size reduction, Medium balances size and clarity, and High produces the smallest file at the cost of visible sharpness.
Is there a file size limit?
Yes. The tool accepts PDF files up to 100 MB. Anything larger will need to be split or reduced by other means before compressing.
What happens when I upload a very large PDF?
Files over about 40 MB trigger a notice warning that compression may take longer and use more of your device’s memory. Keep the tab open and avoid switching apps until it finishes. On a low-memory phone, this can occasionally fail, in which case try again on a computer or pick a higher compression level, which uses a smaller working size per page.
What if compression fails or my browser runs out of memory?
Very large or image-heavy PDFs can use more memory than a device has available, especially on phones. If this happens, close other tabs and apps, try a computer instead of a phone, choose a higher compression level to reduce the working size, or split the PDF into smaller parts first.
Can I compress a PDF to an exact size, like 100KB or 1MB?
Not to an exact number. This tool works by compression level rather than a target file size, so the result depends on how many pages the PDF has and how much detail is on each one. To get as close as possible to a specific size, start with High compression, check the result shown in the summary, and if it is still too large, the file most likely has too many pages or too much detail per page for a single-page target size.
Does this work with password-protected PDFs?
No. A password-protected PDF needs to be unlocked first. The tool detects this case and lets you know rather than failing silently.
Why didn’t my PDF get any smaller?
If a file is already tightly optimised, there may be little or nothing left to compress. In that case the tool will tell you the file could not be reduced further instead of producing a larger result.
Is my PDF uploaded to a server?
No. The file is read and compressed entirely inside your browser. It is never uploaded or stored anywhere.
Is it safe to compress a PDF that contains sensitive information?
Yes. The tool processes your file entirely inside your browser rather than uploading it to a server, so documents containing personal or confidential information never leave your device. Most other online compressors upload your file to a server first, compress it there, then send back the result.
How much can a scanned PDF be compressed?
Scanned PDFs usually compress more than digitally created ones, since every page is already stored as a large image. A 10-page color scan at 300 DPI can be 30 to 50 MB before compression, with reductions toward the higher end of each level afterward. Scanning in grayscale at 150 to 200 DPI keeps the original file smaller from the start.
Can you really compress a PDF without losing any quality?
Not entirely. This tool reduces size by re-encoding each page as a compressed image, which is a lossy method. Claims of “no quality loss” usually mean the loss is small enough to be invisible on screen, not that nothing was removed. Low compression keeps that loss the lightest.
What is Gmail’s or Outlook’s attachment size limit?
Gmail caps total message size, including attachments, at 25 MB. Outlook is typically stricter, around 20 MB. Since attachments are re-encoded for transfer, aim comfortably under the limit rather than right at it.
Can I compress more than one PDF at a time?
The tool processes one PDF at a time. To compress several files, repeat the process for each one, or reset the tool between files.
Does this tool work on mobile devices?
Yes. The tool is fully responsive and works the same way on phones, tablets, and desktop browsers.