Optimize PDF Online — Compare File Size
Re-save a PDF with compact object streams and compare the output size before downloading. This browser-based structural optimization keeps page content intact, but it does not re-compress embedded photos or scans, so the size reduction depends on the PDF.
Select a PDF to optimize
Guide: Compress PDF
This tool optimizes the internal structure of a PDF to make it smaller where it can. It does not recompress the images inside, so the pages look the same, but files full of photos or scans may not get much smaller.
How to use it
- Choose a PDF from your device or drag it into the upload area.
- Check the original file size shown beside the selected file.
- Select Optimize and compare PDF. The tool re-saves the document with PDF object streams enabled; it does not resize or recompress its embedded images.
- Compare the original and output sizes, including the displayed size change.
- If the output is smaller, download it. If it is unchanged or larger, the original may already be optimized or may contain image-heavy pages; keep whichever version suits your needs.
When this tool helps
- Try to bring a PDF closer to an email attachment limit.
- Prepare a file for an upload form that has a size limit.
- Tidy a PDF that has extra internal data from repeated editing.
What it can do
- Optimizes the PDF file structure
- Runs in your browser
- No sign-up needed
Tips for better results
- Compare the new size with the original before you use the file.
- If the file barely shrinks, it is probably mostly images; try a tool that lowers image quality if you can accept that.
- Keep the original until you have checked the compressed PDF.
Limits to know about
- A smaller file is not guaranteed; some PDFs are already well optimized.
- Because images are not recompressed, scanned or photo-heavy PDFs may change very little.
- Password-protected PDFs cannot be processed by this tool.
Frequently asked questions
How much smaller will my PDF get?
It varies. Files with a lot of internal overhead shrink the most, while PDFs full of photos or scans may change very little.
Will compressing lower the quality?
The tool does not recompress images, so the pages look the same. The trade-off is that image-heavy files may not get much smaller.
Why did my file not get smaller?
It may already be optimized, or it may be mostly images, which this tool leaves unchanged.
Is my file uploaded?
No. Compression runs in your browser, and the file is not sent to our server for this tool.