Start with the actual attachment limit
Some forms require a PDF under 1 MB, while email services may allow larger attachments. Check the destination's limit before editing. Compress PDF can reduce some documents, but no compression setting can guarantee that every input fits a particular size.
Why results vary
A scanned PDF may contain large page images that can be reduced. A small text-only PDF may already be compact. Recompressing an optimized document can produce little improvement, and aggressive image reduction may make fine print difficult to read.
- Keep a copy of the original.
- Add the PDF to the compressor and select a suitable setting.
- Download the result and check its actual size in your file manager.
- Open it and inspect small text, diagrams, signatures and stamps.
- Try a stronger setting only if the current output is still too large and readable quality can be preserved.
When compression is not enough
If the source contains unnecessary pages, remove them in a suitable PDF editor before creating a submission copy. If you still have the source images, resize those copies before rebuilding the document with Images to PDF. Do not discard required pages merely to meet a limit.
If the portal permits multiple files, smaller document groups may be more practical than one heavily degraded scan. If it does not, ask the recipient for another submission method. Always keep the readable original for your records.