Government portals, university applications, job sites, and visa forms all do the same thing: they set a hard file-size ceiling and reject anything above it, usually without explaining why. 100 KB, 200 KB, 500 KB, 1 MB, and 2 MB are the common ones. Here’s the order of operations for actually getting under them.
First, find out what’s making the file big
There are only two possibilities, and they have different fixes. Images — a scan, a photo of a document, a report with screenshots — are the case about 90% of the time, and one page of a phone photo can easily be 3 MB on its own; this compresses beautifully. Pages are the other case: a 300-page text document is large because there’s a lot of it, and compression won’t help much — you need fewer pages, not smaller ones. If the file came from a scanner or your camera, it’s images. If it came from Word or a report generator and has no pictures, it’s pages.
Then compress
Run it through Compress PDF. Image-heavy PDFs typically drop by 70–95% — a 6 MB scan landing somewhere around 300–600 KB — while the text stays sharp. If the file genuinely can’t be reduced any further, you get your original back unchanged, which tells you compression isn’t the lever here. For most 1 MB and 2 MB limits, this single step is the whole job.
If you’re still over — the 100 KB and 200 KB cases
Very low limits are usually meant for a single-page document — an ID, a photo, a signature, a certificate — not a multi-page report. Three things help: upload only the page they asked for (split the PDF or delete the pages you don’t need — five pages compressed will never beat one page compressed); rescan in black and white if you’re photographing a printed page, since Scan to PDF in Black & White mode produces a far smaller file than a colour photo of the same page and looks more like a proper scan (tick Compress in the same step); and crop out the background, since desk, hands, and shadows are all detail the file is paying to store, and cropping to the page edge before converting removes it.
The point of the document is that a human can read it, so check that afterward: open the compressed file and zoom to 100% — if the text is legible, you’re fine, and if a serial number or signature has gone mushy, go back and remove pages instead of compressing harder.
A few things quietly make this worse rather than better. Zipping the PDF saves almost nothing, since a PDF is already compressed internally, and most portals reject .zip anyway. Screenshotting the PDF throws away the sharp text and replaces it with a lower-quality picture of it. Re-saving repeatedly mostly degrades quality without much size gain. And uploading a photo renamed to .pdf doesn’t fool anyone — it isn’t one, and the portal will reject it; use Image to PDF to convert properly instead.
If the portal wants a single combined file under one limit, merge your documents first, then compress the merged result — compressing each piece separately and merging afterward usually ends up larger.
Related reading: How to Compress a PDF for Email and How to Share Large Documents Without Email Attachment Limits.
Hit your target with the free Compress PDF tool — no email, no account, and the file isn’t kept anywhere once you’ve downloaded it.