How to use the PDF Compressor
- Drag a PDF into the box above or click it to choose a file. The page count and current file size are shown.
- Choose a compression mode. For ordinary text-heavy documents, try basic optimization first. For scanned documents or photo-heavy PDFs, strong compression is the better choice.
- If you pick strong compression, set the resolution and quality. 100 DPI at 70% quality is a good default for reading on screen.
- Click Compress to see page-by-page progress. When it finishes, check how much smaller the file is, then save it.
Why PDFs get large and how compression works
Most of a PDF's size comes from images. Every page of a document scanned or photographed with a phone is a high-resolution photo, so a scan only needs to pass about 10 pages to reach dozens of megabytes. A PDF saved directly from Word or Google Docs stores its text as vector data, so it starts out small and there isn't much left to compress.
Basic optimization rebuilds the PDF's internal structure. It packs objects into compressed streams and drops unused data, so text and image quality stay exactly the same. It doesn't shrink the images themselves, so the savings usually fall between 0% and 20%, depending on the document.
Strong compression redraws each page as a JPG image at the resolution you choose and builds a new PDF from those images. Converting a 600 DPI scan to 100 DPI cuts the pixel count to about 1/36 of the original, which makes the file much smaller.
Which compression mode to choose
| Document type | Recommended mode | Notes |
|---|---|---|
| Reports made in Word or Google Docs | Basic optimization | Text stays selectable and searchable |
| Scanned contracts, certificates and forms | Strong compression, 100–150 DPI | They're already images, so little is lost |
| Photo-heavy catalogs and portfolios | Strong compression, 100 DPI | 70–80% quality recommended |
| Documents you need to print | Basic optimization or 150 DPI | 72 DPI looks blurry on paper |
After strong compression, you can't copy or search the text. If you might need the text later, save it first with PDF to Text.
Tips for meeting email and upload size limits
- Email attachments and online application portals often have limits such as 10 MB, 20 MB or 25 MB. Try basic optimization first. If the file is still too big, try strong compression at 100 DPI.
- If it's still over the limit, drop to 72 DPI or lower the quality to 50–60%. Small print can be hard to read at 72 DPI, so always check the result before you send it.
- If you only need to send certain pages, extract them with Split PDF before compressing. That's often far more effective.
- If you need to send several files as one, compress each one and then combine them with Merge PDF.