Government portal, job application, insurance claim — every site has its own opinion about PDF size. Most of them are stingier than you'd expect. Your 18MB scan triggers a 'file too large' before you've even clicked submit.
What's actually going wrong
Upload forms set hard size limits, usually between 2MB and 25MB. Anything over the limit is refused outright. The limit is in the form's code, not in your PDF — you can't argue with it. The only path forward is to shrink the file.
The quick fix
Compress PDF in Flint. The compressor downsamples embedded images to screen resolution and rebuilds the structure compactly. Most files come down 60-90%. A 30MB report often becomes 3MB; a 100MB scan often becomes 8MB.
Upload the compressed version. The recipient sees the same content; the server accepts the smaller file.
If that didn't work
Some forms have extreme limits (1-2MB). For those, you may need to combine compression with reducing the document itself. Use split PDF to keep only the relevant pages, then compress. Or convert to JPG at lower resolution and back to PDF for aggressive size reduction.
For uploads where every byte counts, scanning at 200dpi black-and-white instead of colour cuts size dramatically with minimal readability loss for text documents.
Prevent it next time
Always compress before uploading. Scan in black-and-white for text documents. Keep file sizes modest as a habit — most documents don't need to be 30MB.
FAQ
What's a typical upload PDF size limit?
Government portals: 2-10MB common. Job sites: 5-10MB. Insurance: variable. Email-attached: 20-25MB. Aim under 5MB to be safe on most public-facing forms.
How much can Flint shrink my PDF?
Depends on the source. Scans typically lose 80-90% of size. Image-heavy reports lose 60-80%. Text-only documents lose less because there's less to compress.
Does compression reduce visible quality?
Minimally — Flint downsamples images to screen resolution which is invisible during normal reading. Text stays vector-sharp. For uploads where the recipient will only view on screen, the loss is undetectable.
Can I compress a PDF multiple times?
Yes, but with diminishing returns. The first compression captures most savings. A second pass might trim another 5-10% but starts to hurt quality. One round at the right setting is usually enough.
Don't fight upload limits — meet them. Compress in Flint and most PDFs slide right under.