Compress PDF
Shrink file size while keeping it readable.
How to use Compress PDF
- 01
Drop in your PDF
Add the file you want to shrink. It's processed in your browser, so it's never uploaded anywhere.
- 02
Pick a level
Choose Strong, Balanced or Light for a quick preset — or Smart, which finds the most aggressive setting that still passes a readability check.
- 03
Download the smaller file
See the before/after saving and download the result. It's never larger than the file you started with.
Tested and last verified on
About Compress PDF
Reduce the size of image-heavy and scanned PDFs with adjustable quality — or let Smart mode automatically find the most aggressive compression that still passes a real text-recognition readability check. Preview the savings and download a smaller file, all client-side.
Why PDFs get so large — and what compression actually changes
A PDF that weighs tens of megabytes is almost always carrying heavy images: scanned pages saved at a high scanner DPI, photographs pasted in at full camera resolution, or screenshots that were never downsized. The text and vector graphics in a document take up very little space by comparison. That is why two files with the same number of pages can differ wildly in size, and why a compressor's real job is to deal intelligently with images rather than to apply one blunt setting to everything.
This tool works in layers. First it tries a lossless repack that removes redundancy and rewrites the file's internal structure more efficiently — this alone often shrinks text-heavy documents with no change to how they look. Then, for image-heavy and scanned files, it re-renders pages and re-encodes their images at a lower quality, and it keeps whichever version comes out smallest. Because the original file is always one of the candidates, the download is never larger than what you started with.
Choosing a level, and knowing the limits
The Strong, Balanced and Light presets give you direct control over the trade-off between size and image quality, which is ideal when you already know how much fidelity you can spare. Smart mode takes a different approach: it pushes compression as far as it can while a real optical-character-recognition pass confirms the sampled pages are still legible, then stops at the last setting that passed. That makes it the safest choice for scanned documents you still need to read, because it refuses to hand you an illegible file just to hit a smaller number.
It helps to be realistic about what compression can and cannot do. A document that is mostly text is already efficient, so expect only modest savings there. A hard target like a fixed kilobyte cap is not always achievable on a long scanned document without destroying readability — the honest answer in those cases is to reduce the page count or re-scan at a lower resolution. Everything here runs in your browser with no account, no queue and no watermark, so you can try different levels on the same file until the balance of size and quality is right for where you are sending it.
Questions
Everything runs in your browser. How we keep files private
How much smaller can you make my PDF?
It depends entirely on what's inside. Scanned and image-heavy PDFs can shrink dramatically because most of their weight is photos; text-and-vector PDFs are already compact and may only shrink a little. The tool always keeps whichever result is smallest, so you never get a bigger file back.
What does Smart mode do differently?
Instead of guessing a quality level, Smart mode compresses progressively and runs a real text-recognition (OCR) check on sample pages after each attempt, stopping at the most aggressive setting that's still readable. It's slower and needs an internet connection the first time to download the recogniser.
Will compressing blur my document?
Text-based PDFs usually compress with no visible change. Scanned or photo-heavy PDFs trade some image sharpness for size at the stronger settings — Smart mode exists specifically to avoid pushing that too far.
Is my PDF uploaded to compress it?
No. The repack and image recompression both run locally in your browser with WebAssembly, so your document never leaves your device.
Part of: Photo, signature & PDF for exam and job forms
Make your photo, signature and documents fit the form's exact limits.
- Resize a photo or signature to an exact KB sizeHit 20 KB, 50 KB or any limit exactly, with optional exact pixel dimensions. Shows the verified final size.
- Assemble a job or college application into one PDFCombine resume, certificates and ID in order, then check the size and searchable-text status against the portal's limit.
- Assemble visa, loan or KYC documents in the required orderOrder the documents the way the form expects, merge them, and compress to fit the cap in one step.