Why Your PDF Won't Upload — and the 2-Minute Fix

You fill out the whole form, reach the last step, hit upload — and it throws back a red "file exceeds maximum size" error. I've lost count of how many times this has happened to me right before a deadline.

Here's the thing almost nobody tells you: it's rarely the number of pages that's the problem. It's how the PDF was made.

Why scanned PDFs balloon in size

When you scan a document with a phone app or a photocopier, each page is saved as a full-resolution photo tucked inside the PDF. A single scanned page can be 2–4 MB on its own. Three of those and you're already past most portal limits, even though the document is short.

A PDF that was typed (an invoice, a resume you exported from Word) is tiny by comparison, because it's mostly text. So the fix depends on which kind you have.

The fix

Run the file through Compress PDF. It re-optimises the images inside the PDF without touching the text, so the pages stay readable and the size usually drops by half or more. Upload the file, download the smaller one, done — no signup, nothing to install.

If the portal wants something very specific like "under 100 KB", check the result and, if it's still a hair over, compress once more or drop the scan resolution before you make the PDF.

If it started as a photo

A lot of people photograph a document, and then wonder why the PDF is huge. In that case, shrink the photo first with Compress Image to Size — you can tell it an exact target like 100 KB — and only then turn it into a PDF with JPG → PDF. Doing it in that order gives you a clean, small file instead of a bloated one.

A couple of honest caveats

Compression trades a little image sharpness for a much smaller file. For a form or an ID copy that's fine — it stays perfectly legible. For something you'll print at high quality, like a photo you actually want on paper, don't over-compress.

And check the exact limit in the notification before you assume. Some portals cap the whole application, not each file, so a small PDF still helps you stay under the total.

That's really all there is to it. The upload error looks scary, but nine times out of ten it's a 2-minute compress-and-done. More tools here: all PDF tools.