Reduce PDF size for upload
Reducing a PDF for upload begins with the receiver’s rule, not a random compression percentage. Declare the target, make one controlled pass, and inspect the artifact that will actually be submitted.
Capture the real upload rule
A “file too large” message tells you that something failed, but not always which rule caused it. Read the upload field for the maximum size, accepted extensions, page limits, and whether the cap applies to each file or the complete submission.
Write the target down before compression. A percentage reduction is not an acceptance condition; the file either falls below the current portal limit or it does not.
- ■Maximum file size recorded
- ■Accepted file type confirmed
- ■Per-file or total limit known
- ■Current portal instructions checked
Reduce the expensive parts
Images and scans usually dominate PDF size. Remove unnecessary pages, crop scanner borders, and use a clean source. If the file came from a document editor, try its optimized PDF export before converting every page into an image.
UnderLimit rasterizes pages and tries a bounded set of scale and quality profiles. That can help scan-heavy documents, but it may remove interactive forms, selectable text, accessibility tags, links, and signatures that depend on the original PDF structure.
Validate more than size
Check the reported output bytes, open the download, and compare it with the source. Review page order, orientation, names, dates, signatures, fine print, and machine-readable codes.
The receiving portal is the final validator. If it rejects a file already below the stated size, investigate format, encryption, browser, filename, or page rules instead of blindly compressing it again.
- ■Output is below the stated ceiling
- ■Document opens on another viewer
- ■Required details remain legible
- ■Portal completes its own validation
Put the limit first
Run one local compression pass, then inspect every page before submitting.
Open the compressor →