About the PDF Optimizer
The PDF Optimizer loads a PDF and saves it again with a clean internal structure. For some files, such as documents with redundant objects or unused data left by an editing program, the result is slightly smaller.
It is important to be clear about what this tool does not do. It does not recompress images or downsample photos, which is where most large PDFs get their size. So many files will come out about the same size, and a few may even grow a little. If your PDF is large because of scanned pages or photos, a dedicated image-recompression tool will help more.
How to use it
- Click Choose PDF and select a file.
- Press Optimize and download.
- Compare the new file size with the original and keep whichever is smaller.
When this helps, and when it does not
It can help with PDFs that were edited many times or exported with extra metadata. It rarely helps with scans or image-heavy files.
Smaller PDFs for email usually come from lowering image resolution in the program that made the PDF (for example, choosing a "smaller file size" export option).
The tool never changes your original file.
What this tool can and cannot do
A PDF is a container of objects: page descriptions, fonts, images and metadata. Re-saving rewrites those objects in a clean order and can drop unreferenced data left behind by editors. That can make small differences. It does not shrink the images inside, which are usually 90 percent of a large file's size.
Better ways to get a smaller PDF
Export again from the source program using a 'smaller file size' or 'web' option. Scan at 150 to 200 dpi in grayscale for text documents, not 600 dpi in colour. Remove unused fonts and embedded attachments. For a photo-heavy file, compress the photos first with the Image Compressor and rebuild the PDF with Images to PDF.
Examples
A report saved from a word processor with many revisions may drop a few percent. A 20 MB scan will stay about 20 MB. If you need to meet a 2 MB upload limit, re-scan at lower resolution or convert pages to compressed JPEG images and combine them again.
Frequently asked questions
Why is my file not smaller?
The size is mostly images, which this tool does not recompress.
Is it safe for confidential files?
Processing happens in your browser. Still, avoid sensitive documents on shared computers.
Will formatting change?
Pages are copied as they are, so the appearance should stay the same.