How to Compress a Scanned PDF on iPhone to Email It

Last updated 2026-10-29 · Paperkeep Pro feature

Job portals and school forms often cap uploads at something like 5 MB per file. Paperkeep Pro's export screen measures “Original”, “Medium” and “Small” by actually encoding your pages, so you see the real size before you export instead of guessing.

First, with iOS's built-in tools

  1. The Files app has no option to shrink a PDF.
  2. Mail offers a size choice when you attach photos, but not when the attachment is a PDF.
  3. The most iOS alone can do is rescan with the grayscale or black-and-white filter instead of color, which often makes the file smaller.

With Paperkeep

  1. Open the certificate scan and tap “Export…”, the first item in the magic-wand “Tools” menu.
  2. Leave the format on PDF and the real file size is calculated next to “Original”, “Medium” and “Small” under “Size”.
  3. Pick the largest option that's still under the limit; “Medium” usually keeps small print readable.
  4. Tap “Share” to attach it to an email, or “Save to Files” and choose that file on the upload page.
Paperkeep app screen

Tips for this document

  • After choosing “Small”, zoom in on seals and fine print to make sure they're still legible; an unreadable upload may get sent back.
  • If several documents must go in one file, combine them with “Merge” first, then pick the size; the merged size is what you'll upload.
  • Compressing only affects the exported copy. The document in Paperkeep keeps its full quality.

Coming soon to the App Store.

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