PDF Compressor

What this tool does

The PDF Compressor reduces the file size of a PDF by rasterising each page — rendering it to a pixel image at your chosen resolution — then encoding that image as JPEG at your chosen quality level and assembling a new PDF from those images. The result is typically much smaller than the original, especially for text-heavy or mixed-content documents. All processing happens in your browser; nothing is uploaded.

Important trade-off: because each page is converted to an image, the compressed PDF is image-based. Text is no longer selectable, searchable, or accessible to screen readers. This makes it a good fit for archiving, emailing, or sharing documents where reading and printing matter but not searching or copying text. It is not the right approach when you need the document to remain fully text-accessible.

Why you might need it

Many PDFs accumulate size over time — embedded fonts, high-resolution scanned pages, unoptimised images, repeated resources. A single meeting pack can reach 50 MB or more, which exceeds email attachment limits, slows down file sharing platforms, and fills up phone storage when you need a document on the go.

Compressing before you share keeps things practical. A 30-page business report compressed to under 5 MB will email instantly and open quickly on a mobile connection. Scanned receipts and invoices for expense reports can be trimmed from several megabytes to a few hundred kilobytes. Exam papers distributed to students, ebook chapters sent to reviewers, and legal documents shared with clients all benefit from smaller files that open without a wait.

How to use it

1. Drop your PDF onto the dropzone, or click to browse.
2. Adjust the JPEG quality slider. Lower means smaller; 70% is a reasonable default for most documents.
3. Choose an output resolution. 96 dpi is fine for screen reading; use 150 dpi if you plan to print the result and need the text to remain crisp.
4. Click Compress PDF. A progress line shows which page is being processed — large multi-page PDFs take a moment.
5. Review the size summary showing original size, compressed size, and percentage saved.
6. Click Download to save the compressed file.

Common pitfalls

If the compressed file is larger than the original, the PDF was already efficient — it probably contains well-compressed images and no redundant data. In that case try lowering the quality or resolution further. PDFs that consist entirely of small, already-compressed JPEGs will rarely benefit much from this approach.

Very large PDFs — especially those with many high-resolution scanned pages — can take a significant amount of time and browser memory to compress. On a phone or a tablet with limited RAM, a 200-page scanned PDF may be slow or may trigger a browser memory warning. Splitting the PDF first with the PDF Page Extractor and compressing each half separately is a practical workaround.

Tips for best results

Start with the lowest resolution that will be acceptable for the end use. If the document is going to be viewed on screen and never printed, 72 dpi at 60% quality can produce very small files. If it will be printed in an office, 96 dpi at 75% is a reasonable minimum. Reserve 150 dpi for documents where fine print clarity matters, such as certificates or technical plans.

If you need the text to remain searchable after compression, consider whether your original PDF is already compact — sometimes simply re-saving a PDF in Acrobat or an equivalent desktop tool with “optimise” or “reduce file size” removes redundant resources without rasterising anything. This tool is best suited for cases where maximum size reduction is the priority and text access is not.