Compress PDF
Shrink a large PDF by re-encoding its pages as images at a quality you choose. Best for scans and photo-heavy files; the trade-off is that the text stops being selectable.
How to use Compress PDF
- Upload the PDF you want to shrink.
- Choose a compression quality (lower = smaller file).
- Click “Compress” and compare the original vs new size.
- Download the smaller PDF.
About Compress PDF
PDF bloat is nearly always images. A flatbed producing 300 DPI colour pages, or a report carrying a dozen full-bleed photographs, runs to tens of megabytes and collides with the twenty-five megabyte attachment ceiling most mail servers impose. Text costs almost nothing by comparison: a page of prose is a few kilobytes of drawing instructions plus a font subset shared across the whole document. Any honest compressor is therefore attacking the pictures, and the size of the win depends entirely on how much of the file was pictures to begin with.
The method used here is deliberate and blunt. Each page is rendered to a canvas at a set scale, encoded as a JPEG at a set quality, and rebuilt into a new document at the original page dimensions, so the result prints at exactly the size it always did. The three presets are real numbers rather than vague labels: Smaller renders at 1.2× and encodes at quality 0.45, Balanced at 1.5× and 0.65, Better quality at 2× and 0.82. A higher scale keeps detail and costs bytes; a lower quality discards detail and saves them.
The cost is stated plainly because it cannot be undone: once a page has become a picture, its text is no longer selectable, searchable, or readable by a screen reader. For a scanned form that has to be emailed today, this changes nothing at all, since a scan never carried a text layer in the first place. For a contract somebody needs to quote from, a report that must stay searchable, or any document with an accessibility obligation, it is the wrong instrument — keep the original and find another way to send it.
That also explains the most common disappointment. A PDF which is already mostly text will not shrink, and can grow, because you are trading a few kilobytes of efficient vector instructions for a full-page photograph of them. The before-and-after figures are shown rather than hidden for precisely that reason; if the saving does not justify the loss, throw the result away. When a text-heavy file is too big, the productive moves lie elsewhere: extract only the pages you actually need to send, or re-export from the source application with its images downsampled.
Frequently asked questions
How does this compression actually work?
Every page is drawn to a canvas, saved as a JPEG at the quality you selected, and rebuilt into a fresh PDF keeping the original page dimensions. Encrypted files cannot be processed this way, because their contents cannot be rendered until the password is removed.
Will the text still be selectable afterwards?
No. The pages become images, so nothing on them can be selected, searched or read aloud by assistive software. That is an acceptable price for a scan, which never had selectable text, and a poor one for a document people need to quote from.
Why did my PDF barely get smaller?
Because it was mostly text. Vector instructions and a shared font subset are already extremely compact, so replacing them with a photograph of the same page saves little and occasionally costs more. The size comparison reports this honestly instead of hiding it.
Which setting should I choose?
Start with Balanced. Move to Smaller when an email limit is the binding constraint and the document only needs to be legible; move to Better quality when fine print, signatures or diagram labels have to survive. Compare the resulting figures before downloading.
Is my file uploaded to be compressed?
No. Rendering and re-encoding both run in this tab, so the document never crosses the network. That is worth having, given that the files big enough to need shrinking are often scanned personal or financial paperwork.
Does this work on a phone with a large scan?
It does, though it is the most memory-hungry tool here, since each page is rendered at full canvas size before being encoded. On a handset, prefer the Smaller preset, keep the tab in the foreground, and split very long documents before compressing them.
Related tools
- Merge PDF — Combine multiple PDFs into one
- Split PDF — Pull out pages or split into files
- JPG to PDF — Turn images into a PDF
- PDF to JPG — Export pages as images
- Organize PDF Pages — Reorder & delete pages visually
- Rotate PDF — Fix the orientation of pages