PDF size limits show up everywhere - email providers cap attachments around 25MB, but plenty of application portals and online forms are far stricter than that, asking for something under 1MB, or sometimes under 500KB or even 100KB. The gap between "my PDF is 4MB" and "the form wants under 200KB" can feel impossible to close without losing the document entirely.

The good news: PDF compression usually has a lot more headroom than image compression, because most of a PDF's bloat comes from embedded images and inefficient formatting rather than the text itself, which barely takes up any space at all.

What's actually making your PDF huge

Nine times out of ten, it's scanned pages or embedded photos saved at way higher resolution than needed for on-screen reading. A single scanned page at 600 DPI can be several megabytes on its own; the same page at a more reasonable 150-200 DPI (still perfectly readable) might be a fraction of that.

Picking the right compression level for your target

For something like 500KB-1MB, a light-to-medium compression setting is usually enough and keeps text looking crisp. If you need to get down toward 300KB, expect embedded images to lose some fine detail, though text stays sharp since it's stored as vector data rather than pixels. Getting all the way to 100KB is the hardest target and generally only realistic for text-heavy documents with few or no images - a 10-page scanned contract full of photos just isn't going to make it there without becoming unreadable.

If your PDF is mostly scanned images

Compression alone can only do so much. If you have the option, re-scan at a lower DPI to begin with, or convert each page to an image first, resize/compress that image, and rebuild the PDF - tedious, but it works when a straight PDF compressor hits a wall.

Our Compress PDF tool lets you pick a compression level and see the resulting file size before you commit, so you're not stuck guessing and re-uploading. It runs in your browser, so a sensitive document (a contract, a form, a resume) never actually leaves your device.

Dealing with the same size-limit headache for a photo instead of a document? The same crop-first, compress-gradually approach applies - see our guide to hitting tiny image size targets, and if you're specifically filling out a Bangladeshi job or exam form, this breakdown of the exact dimensions those portals expect might save you a few rounds of trial and error.