Government and institutional portals have a particular way of failing. You complete a long form, attach your documents, press submit, and receive a message like “File exceeds maximum size” — with no indication of what the maximum is, which file caused it, or whether the rest of your form has been saved.
The limits themselves are usually modest and often oddly specific: 2 MB, 500 KB per attachment, maximum 20 pages, A4 only, PDF only. They can feel arbitrary. They are usually not, and understanding why they exist makes them easier to meet.
Why the limits are so tight
Portals of this kind are frequently built on infrastructure that has to last a decade or more, serve enormous numbers of people simultaneously during deadline periods, and store every submission for a legally mandated retention period — sometimes seven years, sometimes permanently.
A limit of 2 MB per attachment across a few million submissions a year is a storage commitment measured in terabytes, retained indefinitely, backed up, and subject to audit. Doubling the limit doubles that permanently. The constraint is real, even when the number feels stingy.
Page size requirements have a different origin. Documents that may need to be printed for a physical file, or processed by automated systems expecting a known geometry, have to be predictable. A PDF whose pages are 3024 × 4032 points because that is what a phone camera produced will break a print queue and can defeat automated extraction. Some portals genuinely validate this, and reject files that fail.
Work out what you are actually fighting
Before compressing anything, check three things. It takes a minute and often changes the approach entirely.
Read the limit carefully. There is a real difference between “2 MB total” and “2 MB per attachment”, and between “maximum 20 pages” and “maximum 20 pages per document”. Portals are frequently ambiguous about which they mean, and the difference can be the whole problem.
Find out whether multiple files are allowed. Many portals that impose a small per-file limit accept several attachments. If so, splitting a document is far better than compressing it into illegibility, and it is the first thing to try.
Check what is inflating your file. Open it and try to select text. If words highlight, it is a digital document and the size is coming from images or accumulated revisions. If nothing highlights, it is a scan, and resolution is the lever.
The order that produces the best result
There is a reliable sequence, and following it means you only degrade quality as a last resort rather than as a first move.
One: remove pages that carry nothing. Blank sheets from a duplex scanner, cover pages, separator sheets, the scanner’s calibration page. This is completely lossless and on a typical scanned bundle removes 10 to 40 per cent of the file. Delete them and re-check the size before doing anything else.
Two: send only what was asked for. If the form asks for proof of address and you have an eighteen-page bank statement, the one page showing your address is what they need. Extracting it is lossless, smaller, faster to review, and discloses less about you. This step alone resolves a surprising share of size problems.
Three: try structural compression. This rewrites the file’s internals — merging duplicated objects, dropping superseded revisions — with no change whatsoever to appearance. Text stays selectable. On a document that has been edited repeatedly it can remove 40 per cent. On a freshly exported one it may do nothing. It costs nothing to try.
Four: only now, reduce image quality. If the document is a scan, rasterising at a sensible resolution is where the large savings are. Start at 150 DPI with greyscale enabled, check the result, and step down to 120 only if needed.
The specific settings that hit 2 MB
For a scanned document of ten to twenty pages, this progression works reliably. Stop as soon as you are under the limit.
| Step | Resolution | Colour | Typical result |
|---|---|---|---|
| Start | 150 DPI | Greyscale | Readable, prints acceptably |
| If still large | 120 DPI | Greyscale | Comfortable on screen |
| If still large | 96 DPI | Greyscale | Small print starts to soften |
| Last resort | 96 DPI | Black & white | Text only, no photographs |
Take savings from resolution before quality. Halving the resolution removes three-quarters of the pixels; reducing JPEG quality from 80 to 50 saves far less and introduces visible artefacts around letter edges, which is exactly where legibility lives.
Greyscale is the most under-used setting available. Most scanned documents are black text on white paper recorded in colour by default. Converting to greyscale routinely halves the file again with nothing lost — provided there is no colour that carries meaning, such as a blue-ink signature that proves the document is not a photocopy.
Below 96 DPI, stop. A document that uploads successfully and cannot be read has failed, it has just failed later and more expensively. If you are at 96 DPI and still over the limit, the document is too long rather than too heavy — split it.
Meeting page-size requirements
If a portal specifies A4 or Letter, and your document came from a phone camera, it almost certainly does not comply.
The fix is at conversion time. When turning images into a PDF, choose A4 or Letter rather than fit-to-image. Each photograph is then scaled onto a standard sheet with a margin. Keep the margin at 24 points or more — home and office printers cannot print to the edge of a sheet, and a document destined for a physical file will be clipped otherwise.
If you already have a non-compliant PDF, converting it to images and rebuilding at the correct page size works, at the cost of the text layer. Better to redo the conversion from your original images if you still have them.
Splitting as the better answer
Where multiple attachments are allowed, splitting beats compressing every time. Four readable 1.5 MB files serve everyone better than one barely-legible 2 MB file.
Two things make split submissions work smoothly. Number the parts in the filename with
zero-padding — application-part-01, application-part-02 — so they sort correctly in any listing.
And upload them in order, because some portals display attachments in upload sequence rather than
by name.
If the portal takes only one file but caps the page count, splitting into fixed chunks that clear both limits and submitting them across multiple attachment slots is usually faster than arguing with the form.
When the limit is genuinely impossible
Occasionally the requirement cannot be met honestly: a 500 KB limit on a fifty-page scanned document, or an accepted format your source material cannot produce.
At that point, stop optimising and contact them. Portal limits are set by policy, and the people administering the process usually have a documented alternative — a secure upload channel, an email address for oversized submissions, a physical delivery option, or the authority to grant an exception. Every institution that imposes a 2 MB limit receives documents that cannot meet it, and they have a procedure.
Ask before the deadline rather than after. An email sent a week early asking how to submit a large document is a routine administrative query. The same email sent an hour before the deadline is a problem.
Before you press submit
Open the final file and look at the smallest text on the busiest page at full magnification. Check the corners, where reference numbers and stamps live. Confirm the pages are in order and the right way up.
Then keep the original. The compressed version is for submission; the original is what you will need if anyone asks for a clearer copy, and once you have compressed over the top of it, there is no way back.
Compress PDF shows the exact before and after size so you can meet a limit precisely, and it runs in your browser — which matters when the document is an identity paper or a bank statement.