Compress PDF Online
Reduce PDF file size
in seconds — free
Shrink any PDF directly in your browser. No upload to a server, no account required. Compress PDF files and download the smaller version instantly.
File never leaves your device
What gets compressed
Images & photos
Embedded JPEG and PNG images are downsampled and re-compressed. This alone accounts for 80–95% of typical PDF bloat, as noted by HowToGeek in their PDF size reduction guide.
Content streams
All object streams are compressed with Flate (zlib) encoding, reducing the raw data size without altering the content — the same technique used by tools like Soda PDF and PDFGear.
Redundant data
Unused objects, duplicate resources, and bloated metadata are removed from the file structure before export. Unlike ilovepdf or Adobe Acrobat online, this runs entirely in your browser — no server upload.
Tips to make PDFs smaller
- Reduce image resolution — for on-screen reading, 72 dpi is sufficient; for print, 150 dpi is still half the size of a 300 dpi export. Lifewire recommends this as the first step for most users.
- Use JPEG for photos — JPEG compresses photographs 10× better than PNG for similar visual quality.
- Remove embedded fonts you don't need — font subsetting keeps only the characters used in the document, a technique well documented by Smallpdf's compression guide.
- Flatten unnecessary layers — merge all overlays and annotations to reduce object count in the file.
- Strip metadata — XMP and Document Information Dictionary fields can add tens of kilobytes to a small file.
Learn more in our guide: How to reduce PDF file size without losing quality.
Frequently asked questions
How do I compress a PDF to make it smaller?
Open the PDF in the editor, then click Download PDF and choose the "Optimise for web" or "Compress" export option. The editor reduces image quality and removes redundant data. For maximum compression, also reduce image resolution before inserting images into the document.
How do I reduce PDF file size without losing quality?
Use the editor's export compression set to "Balanced" — this applies Flate/JPEG compression to image streams while keeping text and vector graphics at full resolution. As HowToGeek details, image downsampling is the single highest-impact step — most PDF bloat comes from unnecessarily high-resolution embedded images.
How can I make a PDF smaller?
Three techniques work best: (1) downsample embedded images to screen resolution (72–150 dpi), (2) remove unused objects and metadata, (3) apply Flate stream compression to all content streams. The editor applies all three automatically when you use the compressed download option. Our article How to reduce PDF file size without losing quality covers each technique in detail.
How does this compare to ilovepdf or Adobe for compressing PDFs?
ilovepdf.com and Adobe Acrobat online both compress PDFs, but upload your file to their servers. Soda PDF and PDFGear are desktop alternatives. PDFTheGuide compresses entirely in your browser — your file never leaves your device.
How do I shrink a PDF file size?
Use the free online PDF compressor: open your file, click Download, and select the compressed export. No upload to any server — compression runs entirely in your browser. Lifewire's guide to reducing PDF size also recommends browser-based tools as the simplest approach for most users.
Is there a limit on the file size I can compress?
No server-imposed limit. The practical limit is your device's available memory. Files up to 50 MB compress reliably in most modern browsers.
Does compressing a PDF damage the content?
No. Text, bookmarks, form fields, and vector graphics are lossless. Only raster image quality may be reduced slightly at higher compression levels — the trade-off is always visible before you download.