What does a PDF compressor do?
A PDF compressor shrinks a PDF's file size, usually by re-encoding the images and page content more efficiently. This tool works by rendering each page at a chosen resolution and re-encoding it as an optimized JPEG, then rebuilding a new PDF from those pages - the same approach used by most desktop and server-side PDF compressors, done entirely in your browser. A 20 MB scanned report can often drop to a few megabytes with the eBook preset and still be perfectly readable.
Presets vs. target file size
Use the Screen, eBook, and Print presets for a quick, predictable result: Screen (96 DPI) gives the smallest files for sharing links or email, eBook (150 DPI) is a solid default for reading on a tablet or laptop, and Print (300 DPI) keeps the most detail for documents you plan to print. Pick Custom to set your own resolution and quality.
Use target file size when you have a hard limit to hit - an upload cap, an email attachment limit, or a specific size budget. The tool samples a few pages at different quality levels, estimates the final size, and picks the highest quality that should land at or under your target before rebuilding the full file.
Reading the size estimate and page preview
As soon as your files load, an estimated output size appears based on a quick sample of each file's first page - useful for judging a preset before running a full compression pass, especially on large batches. After compressing, click Preview on any row to compare the original page against the compressed page side by side, along with the exact resolution and quality used.
What compressing changes
Because each page is re-rendered as an image, the output PDF is no longer text-searchable or selectable, even if the original was. This is the trade-off that makes the file smaller. If you need to keep selectable text, work from a copy and keep the original PDF as your source of truth, or use a higher Print-quality setting where detail loss matters less than the format change.
How to compress a PDF
- Drop one or more PDF files onto the drop zone, or click Browse files.
- Pick a preset, adjust Custom resolution/quality, or enable target file size.
- Check the estimated output size, then click Compress.
- Preview a result, then download it individually or grab everything as a ZIP.
Common uses
Email and upload limits
Many forms and email providers cap attachments at a few MB. Use target file size mode to land safely under the limit without guessing at a resolution.
Scanned documents and reports
Scanned PDFs are often unnecessarily high-resolution. The Screen or eBook preset can cut file size dramatically while staying readable on any device.
Batch cleanup
Drop a folder of PDFs, apply one preset to all of them, and download the whole set as a ZIP in one click.
Frequently asked questions
Does compressing a PDF upload my file anywhere?
No. Every page is rendered, re-encoded and reassembled into a new PDF entirely inside your browser. Your file never leaves your device.
Will the text still be selectable after compressing?
No. This tool compresses by re-rendering each page as an optimized image, which is where most of the file-size savings come from. That means text is no longer selectable or searchable in the output. Keep the original PDF if you need selectable text later.
How does target file size mode work?
The tool samples a few pages at different quality levels to estimate how big the final file will be, narrows in on the highest quality that should land at or under your target, then rebuilds the whole PDF at that quality.
Why is my compressed file larger than the original?
This can happen with PDFs that are already heavily compressed, mostly text with few images, or very small files. Try a lower-resolution preset, or keep the original if compression isn't helping.
Is there a limit to how many PDFs I can compress?
No limit. Files are processed one at a time so memory stays manageable even with large batches.