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 how to actually get under them.
Step 1: 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, or a report with screenshots. One page of a phone photo can easily be 3 MB on its own. This is the case about 90% of the time, and it compresses beautifully.
- Pages. A 300-page text document is large because there’s a lot of it. Compression won’t help much; you need fewer pages.
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.
Step 2: 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.
Step 3: 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. If you’re fighting a 100 KB limit:
- 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 & White. If you’re photographing a printed page, 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.
- Crop out the background. Desk, hands, and shadows are all detail the file is paying to store. Cropping to the page edge before converting removes it.
Step 4: Check it’s still readable
The point of the document is that a human can read it. After compressing, open the file and zoom to 100% — if the text is legible, you’re fine. If a serial number or signature has gone mushy, go back and remove pages instead of compressing harder.
Common mistakes
- Zipping the PDF. A PDF is already compressed internally; a ZIP saves almost nothing, and most portals reject .zip anyway.
- Screenshotting the PDF. This throws away the sharp text and replaces it with a lower-quality picture of it.
- Re-saving repeatedly. Compressing an already-compressed file mostly degrades quality without much size gain.
- Uploading a photo renamed to .pdf. It isn’t one, and the portal will reject it. Use Image to PDF to convert properly.
If the portal wants one file
Many forms ask for a single combined PDF under one limit. Merge your documents first, then compress the merged file — compressing each piece separately and merging afterwards usually ends up larger.
Ready? Try the free Compress PDF tool now — no sign-up, no watermark, and your file is never stored.