A PDF that is too large to attach can slow down a simple handoff. Before compressing it, check the size limit shown by the recipient or upload form. There is no single attachment size that fits every email service, account or workplace rule.
Try simple changes first
If you created the document, export another copy with smaller photos or an optimized-for-screen setting. If only some pages are needed, make a separate PDF containing those pages. Keep the complete original. These steps can reduce the file without recompressing every page.
Compress a PDF in your browser
- Open the PDFMochi PDF compressor and choose the file.
- Select a resolution and image quality. Low favors a smaller copy; Balanced is a middle setting; High keeps more visual detail and may create a larger file.
- Compress the document and compare the output size with the original.
- Open the downloaded copy at normal reading size. Check the smallest text, tables, stamps and signatures before emailing it.
- If anything is too soft to read, use a higher setting or a different method.
Understand what changes
This compressor renders every page as an image and builds a new PDF from those images. That can help some scan-heavy files. It is a lossy conversion: text is no longer selectable or searchable, and links, form fields, accessibility tags and digital signatures are not preserved. An already optimized PDF can even become larger.
The selected PDF is processed in your browser. The site loads its PDF libraries from third-party content delivery networks, but the selected document itself is not sent to a PDFMochi processing server. Large files still use device memory and may take longer on older phones or computers.
Keep the original safe
Save the compressed file as a new copy. Do not replace a signed, accessible or archival source with an image-only version. If the compressed output is not readable or does not meet the size limit, keep the original and choose another sharing method.
Frequently asked questions
Will compressing always shrink my PDF?
No. Results depend on the source, resolution and image quality. Compare the new file before sending it.
Can the recipient search the compressed PDF?
Not with this image-based method. The page text is not retained as selectable text.