Compress PDF Files Online and Free
Our free PDF compressor reduces PDF file size in seconds, so it's small enough to email, upload, or store. Shrink a PDF without losing quality. Basic, Strong, or Custom control. No sign-up. No watermark. Files deleted within 1 hour.
- Free, fast, and secure. No account required.
- Compress toward an exact target size, down to 20 KB.
- Works on Mac, Windows, iPhone, and Android in any browser.
or drop your first file here
Up to 4 files · 100 MB each · Free
Files deleted within 1 hour. We don't index your file contents or use them to train AI.
Files deleted after 1 hour
HTTPS encryption in transit. We never train AI on your file contents.
Compress in Under 30 Seconds
Most files finish at once. The compressor handles PDFs over 50 MB.
No Sign-Up, No Watermark
Free. No trial nag. No email gate. No quality limits.
Quality You Control
Basic keeps it near-lossless. Strong goes smallest. Custom is yours.
Compress PDF to a Specific Size
Contract portals, government forms, and email limits often cap uploads at a fixed size. Pick your target and we compress toward that ceiling.
How To Compress a PDF Online
Three steps. No installs. No accounts. No hidden limits.
Upload Your PDF
Drag your file into the box above, or click to browse. You can compress up to 4 files, 100 MB each.
Choose a Preset
Pick Basic for a balanced reduction, Strong for the smallest file, or Custom to set DPI, grayscale, or remove images.
Compress and Download
Click Compress PDF. Your smaller file is ready in seconds. No watermark.
Why Compress PDFs With PDFNoob?
We benchmarked sixteen PDF tools. Here is what makes ours different.
Truly Free, No Asterisks
No file cap. No signup wall. No Pro upsell to unlock stronger compression or remove a watermark.
Compress to a Target Size
Hit an exact ceiling like 1 MB, 500 KB, or 100 KB, instead of hoping a single slider lands under the limit.
Custom Control
Set image DPI, convert to grayscale, strip bookmarks, or remove images entirely for a text-only file.
Works on Any Device
Browser-based, so it runs on Mac, Windows, iPhone, and Android with nothing to install.
Privacy by Design
Files delete within one hour. We don't index file contents. We never use them to train AI.
Fast, Batch Ready
Drop up to four PDFs and compress them in one go. Most files finish in a few seconds.
About PDF Compression
Compressing a PDF means shrinking the objects inside it that take up the most room, while keeping the document readable. Whatever you call it (shrink PDF, resize PDF, or make a PDF smaller), it comes down to the same thing. A PDF is a container of page objects: text, fonts, images, and metadata. Compression works on each of these differently, and how much you save depends on what your file is made of.
Images Are the Main Target
In most oversized PDFs, images are the culprit. A single full-page scan at 600 DPI can be larger than an entire text document. A PDF compressor downsamples those images to a sensible resolution and re-encodes them efficiently, which is where the biggest reductions come from. Downsampling images is the single fastest way to reduce PDF size. A scanned contract shrinks dramatically while a plain text report barely moves.
Lossy vs. Lossless: Which Should You Choose?
Basic is near-lossless: it strips redundant data, subsets fonts, and applies light image optimisation without visibly changing the page. Strong downsamples images more aggressively to reach a smaller size, so photo-heavy files may soften slightly. Text and vector graphics stay sharp in both modes because they are not stored as pixels.
When to Use the Custom Preset
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Set Image DPI. Lower DPI means a smaller file; 96 for screen, 150 for print, 300 for high quality.
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Convert to grayscale. Drops colour data, good for printing or sharing where colour isn't needed.
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Remove images. Deletes every picture for a text-only file that is dramatically smaller.
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Remove bookmarks. Strips the outline tree when you only need the pages.
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Frequently Asked Questions
Common questions about compressing PDF files online.
How Do I Compress a PDF for Free?
Upload your PDF to the compressor above. Choose Basic, Strong, or Custom, then click Compress PDF. Your smaller file downloads at once. No account is needed. The output carries no watermark.
How Does PDF Compression Work?
The compressor shrinks the parts of the PDF that take up the most space. It downsamples and re-encodes images, subsets embedded fonts to keep only the characters you use, removes duplicate data, and re-compresses the file structure. Text stays sharp because it isn't stored as an image.
Will Compressing a PDF Reduce Its Quality?
Basic is close to lossless, so most people see no difference. Strong downsamples images more to hit a smaller size, so photo-heavy files may soften slightly. Text and vector graphics stay crisp either way.
Can I Compress a PDF to a Specific Size?
Yes. Use a target-size tool such as Compress PDF to 100KB, to 500KB, to 1MB, or to 2MB. Each compresses toward that exact ceiling, which is useful for upload limits on forms, portals, and email.
Why Is My PDF File So Big?
Usually because of images. High-resolution scans and photos are the largest objects in a PDF. Embedded fonts, thumbnails, and stored metadata add more. A text-only PDF is small; add a few full-page scans and it balloons, which is exactly what compression targets.
What Does the Custom Preset Do?
Custom gives you manual control. Set the image DPI, convert the document to grayscale, remove all images for a text-only file, or strip bookmarks. Combine them to hit the exact size and quality you need.
Is It Safe to Compress a PDF Online?
Yes. Files travel over an encrypted HTTPS connection. We delete them within one hour. We don't index your file contents. We never use them to train AI. If you prefer never to upload at all, our desktop app compresses entirely on your computer.
Does It Work on iPhone, iPad, or Android?
Yes. PDFNoob is a web app. No install is needed. Open this page in Safari or Chrome. Pick your PDF from Files, Photos, or Drive, and the compressed file saves back to your phone the same way.