I have a 30-page scanned PDF too big for a portal that only takes files under 10 MB, and the online reducers I tried either failed or made it unreadable. Is there one that works?
I agree, that is annoying. Honestly, most online reducers either fail on scanned files or make the text unreadable, because a scan is just pictures. If you still have the paper, rescan at 150 dpi in black and white or grayscale; a 30-page file usually drops under 10 MB. If you only have the PDF, try opening it in Word and saving as PDF, or use Microsoft Print to PDF.
Scanned pages are basicly just photos, so most reducers fail because they only strip metadata. I run mine through ilovepdf’s compress on the extreme setting and 30 pages usually lands well under 10 MB. If it’s still too big, what dpi were the scans done at? Dropping to 150 dpi makes a huge difference.
Try PDF24’s Compress PDF and choose medium compression, then check the smallest text before uploading. If it is still over 10 MB, convert the scans to greyscale first; avoid maximum compression, as it usually turns small print into mush.
Honestly, for a scanned PDF I would rescan at 150 to 200 dpi in grayscale, which usually gets 30 pages under 10 MB while keeping text readable. If rescanning is not possible, try exporting from Preview on a Mac with reduced quality. Avoid repeated compression, because it quickly makes scanned text fuzzy.
@ashley.cardiff is spot on about rescanning! Those portal limits are so stresful when uploading large vendor invoices, but the Microsoft Print to PDF trick you mentioned always shrinks down my chunky layout files. Are you guys using Windows devices?
@Rando72836 Windows here. Rescanning is what I do too, 150 dpi greyscale, so the text stays sharp. If it is still over the limit, split the scan into two files rather than compressing twice, and keep a backup of the original before you shrink anything.
For scanned PDFs the trick is lowering image resolution, not just “compressing.” I use PDFcap and drop it to like 150 dpi, keeps 30 pages readable and way under 10 MB.
pdfcap usually works better for scanned files since you can compress the images instead of just crushing the whole PDF. Try medium image quality first, then check a couple pages at 100% before uploading, especially any small text. Is it mostly black-and-white forms or color scans?
Honestly, scanned PDFs are the worst for this since they’re basically images. I run into the same thing with drawing sets. Try smallpdf or ilovepdf first, but if it stays unreadable, rescan at 200 dpi instead of 300 and the file drops way down. What did the portal say when it failed, size error or corrupted file?