October 1, 2026 · 7 min read

How to Make a PDF Smaller for an Online Form

Portals cap uploads at 2 or 5 MB and your PDF is 20. How to get it under the limit, and when compressing quietly destroys the selectable text layer.

Government portals, HR systems, visa applications, tax filings and university forms all share a habit: a hard upload limit, stated in small print, with no explanation of how to meet it. You export your document, it comes out at 18 MB, the box says 5 MB maximum, and the Browse button is the only thing on the page that works. The good news is that oversized PDFs are nearly always big for one of three reasons, and each has a different fix.

First, work out which kind of PDF you have

This is the step everyone skips, and it decides everything that follows. Open the file and try to select a line of text with your cursor.

A text PDF of a ten-page letter should be a few hundred kilobytes. If yours is 18 MB, there are photographs or screenshots in it at print resolution, and those are what you need to deal with — not the text.

The cheapest fixes, in order

• Re-export from the source. In Word, Pages or Google Docs, export to PDF rather than printing to PDF, and if you have the option, pick a screen or web preset instead of print.
• Shrink the images before you place them. A 12-megapixel photo dropped into a document is still 12 megapixels inside the PDF, even though it prints at postcard size.
• Remove what the form doesn't need. Cover pages, a decorative header on every page, an embedded font you used for one heading, a blank final page.
• Split the submission. Many portals cap each file rather than the application, and will take three 4 MB files where they refused one 12 MB file.
• Check whether they even want a PDF. Some portals accept a JPG for an ID photo, which is far smaller than the same image wrapped in a PDF.

The trade-off worth understanding before you compress

PDF compression is two very different operations wearing the same button. We'd rather be plain about which one you're getting.

• Lossless re-saving repacks the file's internal structure and strips document metadata. Nothing on the page changes, selectable text stays selectable, and the saving is modest — sometimes a few percent, occasionally much more on a badly built file. It costs you nothing, so it's always the first thing to try.
• Rasterising renders every page to an image at a chosen resolution and rebuilds the PDF from those pictures. This is where the dramatic reductions come from. It is also irreversible: the text is now a photograph of text, so nobody can select, copy or search it, and the page will look slightly soft.

In Skrubly's compressor, Light is the lossless re-save and keeps your text layer. Balanced and Strong rasterise the pages at roughly 120 and 96 DPI. For a scan — which was already a picture — that's often a reasonable trade. For a CV, a contract or a form with real text in it, rasterising is a downgrade you can't undo, and some systems will reject the result.

When the text layer actually matters

• Applicant tracking systems read the text of your CV. An image-only CV can parse as empty.
• Any form that says "searchable PDF" or "machine-readable" is asking for a text layer explicitly.
• Accessibility: a screen reader can read a text PDF and cannot read a picture of one.
• Your own future self, trying to find a clause or a reference number in a 40-page contract.

If you need both small and searchable, the order is: OCR or keep the text first, compress the images inside the document, and avoid rasterising at all. If you do rasterise and still need searchability, you'll have to run OCR over the result — which works, but on a softened image it works less well.

Checks before you press Submit

• Open the compressed file, zoom to 100 percent, and read the smallest things on the page: footnotes, reference numbers, dates, the difference between an 8 and a 3.
• Confirm the page count didn't change and nothing got rotated.
• Check the filename. Plain letters, numbers, hyphens — some portals choke on accents, spaces or very long names.
• Look at the document properties. PDFs carry an author name, a title and the name of the software that made them, which is often someone else's name if you reused a template.
• Submit with time to spare. If a 95-percent-complete upload fails, it's frequently a timeout rather than the size limit — and a smaller file fixes both.