Where 5 MB limits come from
Portals cap file sizes to keep uploads reliable on slow connections and storage manageable. Australian examples, as commonly reported: ImmiAccount at about 5 MB per attachment, and the Child Support online account at under 5 MB per file. Centrelink allows under 10 MB per upload in total. We could not confirm every figure on the official pages, so check the portal; it usually says so next to the upload button. Aim for about 4.5 MB to leave a margin.
Step 1: try light compression
Open the PDF compressor, leave the mode on Light, and run it. Light mode removes waste (unused objects, thumbnails, metadata) and keeps text selectable. On PDFs exported from Word or edited several times it can halve the size. On scans it usually does little, because scans are mostly image data.
Step 2: strong mode with a target
Switch to Strong, tick Aim for a target size and enter 4.5. The tool renders every page, measures how big it would be at 200, 150, 110 and 80 dpi and at four JPEG qualities, and picks the sharpest setting that fits. For a typical scanned document, 150 dpi at quality 60–70 is about 150–300 KB per A4 page, so twenty pages fit in 5 MB comfortably.
Strong mode turns pages into images. Scans were images already, so nothing is lost; for typed documents, text stops being selectable. If the portal or the reader needs selectable text, see step 4.
Rough sizes to expect
| Content (A4) | 150 dpi, quality 70 | 110 dpi, quality 60 |
|---|---|---|
| Typed letter, black on white | 100–200 KB | 60–120 KB |
| Scanned form with handwriting | 150–300 KB | 90–180 KB |
| Full-colour photo page | 300–600 KB | 180–350 KB |
These are typical ranges, not guarantees; complex pages compress less.
Step 3: if it still will not fit
- Split it. Many portals accept several files. Split by size with a 4.5 MB limit groups pages into parts under the cap without touching quality.
- Remove what is not needed. Delete blank pages, duplicate scans and pages the portal did not ask for.
- Rescan smarter. 150 dpi greyscale scans of text documents are small from the start; 600 dpi colour scans are not.
Step 4: keeping text selectable
If you must keep selectable text and light mode is not enough, the large part of the file is almost always embedded images. Re-export the document from its source (Word, Pages, Google Docs) with a "smaller file size" or "minimum size" PDF option, which compresses the images while keeping the text. Or compress the images before inserting them.
Check before you submit
- Open the compressed file and zoom to 100%. Small print, stamps and signatures must be legible.
- Check the page count matches the original.
- Check the size in your file manager, not just the browser's download bar.
Everything here runs in your browser, so the documents you are compressing (often passports, statements and certificates) are never uploaded to do it.
When a portal counts total size
Some portals limit each file; others limit the total of an upload. As reported, Centrelink counts all files in one upload together, under 10 MB. Compress each file with a target that leaves room for the others, or upload in several batches if the portal allows it.
Colour or greyscale?
A colour scan of a black-and-white document stores three colour channels for nothing. If your scanner app offers greyscale or "document" mode, use it for text documents: the file starts smaller and compresses further.
Keep a full-quality copy
Submit the compressed file, but keep the original. Assessors sometimes ask for a clearer copy of one document, and you can send it without rescanning.