How to prepare a PDF for an upload portal

Start with the portal's rules

Before touching any file, write down exactly what the portal asks for. The rules differ from one site to the next, and most rejections come from missing one of them rather than from a problem with the documents themselves. Look for:

• How many files. Some portals want one PDF containing everything; others want one file per document, each in its own upload slot.
• Maximum file size, per file and sometimes in total. Limits of a few megabytes are common, especially on government sites.
• Accepted formats. Usually PDF, sometimes also JPG or PNG; occasionally only images for things like passport photos or ID scans.
• Page limits, for example "no more than 10 pages" for a statement or "first two pages of the bank statement only".
• Order, if they specify one — application form first, then identity documents, then supporting evidence.
• Whether the file may be password-protected. Almost always it may not.

Keep this list open while you work, and check the finished file against it at the end.

Gather and check each file

Put every document in one folder and open each one briefly. Three problems are worth catching now, because they are awkward to fix later.

Password protection

Bank statements and payslips downloaded from online banking are often protected. Portals reject encrypted PDFs because their systems cannot read them, and merging tools cannot copy pages out of them either. Open the file in your PDF reader with its password and use Save As or Print to PDF to make an unprotected copy. The merge tool on this site tells you which file is protected rather than producing a broken result.

Files that are not really PDFs

A photo renamed to .pdf is still a photo. So is a file that only partly downloaded. Opening each file once catches both. If a document only exists as a phone photo, it is better to scan it properly with a scanning app, which straightens the page and increases contrast, than to convert the photo.

Legibility

Zoom in on the smallest text of each scan. If you cannot read it on screen, the person reviewing your application cannot either, and some portals run automatic checks that reject blurred pages. Rescan at a higher resolution rather than trying to sharpen the image afterwards.

Fix orientation and remove stray pages

Scanners and phone apps frequently save a page sideways or upside down, and double-sided scanning adds blank backs. Open each file in Organize PDF. You will see every page as a thumbnail:

• Rotate sideways or upside-down pages with the rotate buttons. Rotation only changes a setting on the page, so it costs no quality.
• Delete blank pages and pages that should not be sent — the terms and conditions at the end of a statement, for example.
• Drag pages into the right order if the scanner mixed them up.

Save the result; it downloads as a new file ending in -organized.pdf, and the original stays untouched. For a double-sided scan where every second page is blank, you can instead list the odd pages directly when merging: 1, 3, 5, 7 for an eight-page scan.

Merge in the right order

If the portal wants a single file, open Merge PDF and add all the documents. Put them in the order the portal asks for, or, if it does not say, in the order a reviewer would want to read them: the application form, identity documents, then supporting evidence in the order the form refers to it.

Each file can contribute only some of its pages. Type the pages into its box: 2- drops a cover page, 1-2 keeps only the first two pages of a long statement. Merging copies pages without re-rendering them, so text stays sharp and selectable, which also helps reviewers who search the document.

Check the summary line before merging: it shows how many files and pages will go in. A three-page form plus a two-page certificate should give five pages; if it does not, a page range is wrong.

Stay under the size limit

The size of a PDF is almost entirely the size of its images. A page of typed text takes a few kilobytes; a scanned page can take several megabytes depending on how it was scanned. Merging and reordering do not change the size of individual pages, so a merged file is about as large as its parts added together.

If the result is over the limit, the most effective fix is at the source: rescan at a lower resolution or in greyscale instead of colour. Most scanning apps offer 150 or 200 DPI, which is plenty for printed text; 300 DPI and colour are needed only for photographs or fine print. If the portal allows several files, the other option is to split the document with Split PDF — by ranges such as 1-12, 13-24, 25-30, which produces three files of 12, 12 and 6 pages, or by a fixed number of pages each.

Avoid online "compressors" that upload your file: identity documents and bank statements are exactly the files you should not send to an unknown server.

When the portal wants images

Some upload slots accept only JPG or PNG — often for identity documents or a single signed page. Use PDF to image and choose the pages you need. The resolution setting decides the pixel size: an A4 page becomes 1,240 × 1,754 pixels at 150 DPI and 2,480 × 3,508 at 300 DPI; a US Letter page becomes 1,275 × 1,650 at 150 DPI. If the portal specifies pixel dimensions, pick the DPI that gets closest without going under.

Choose PNG for pages that are mostly text and JPG for photographs or when the file must be small. Remember that an image of a page is no longer searchable; keep the PDF for any slot that accepts it.

A worked example

Suppose a graduate programme asks for one PDF containing the application form, passport, transcript, proof of funds and a language certificate, in that order. What you actually have is:

The steps: save an unprotected copy of the bank statement from your PDF reader; rotate the passport page in Organize PDF; then add all five files to Merge PDF in the required order, typing 1, 3, 5, 7 for the transcript and 1-2 for the statement. The summary should read 5 files and 12 pages (3 + 1 + 4 + 2 + 2). The landscape certificate pages stay landscape — a merged PDF can mix page sizes and orientations — so reviewers can read them without turning their heads.

If the portal later says the file is too large, the scanned pages (passport and transcript) are almost certainly the culprits; rescanning just those two at 150 DPI in greyscale usually fixes it without touching the rest.

The final check

1. Open the finished file in an ordinary PDF reader, not just the tool that made it.
2. Scroll through every page: right way up, in order, nothing missing, nothing extra.
3. Check the page count and file size against the portal's rules.
4. Name the file the way the portal asks, or, if it does not say, descriptively: Surname_Firstname_Application.pdf is kinder to a reviewer than merged (3).pdf.
5. Keep a copy of exactly what you uploaded.

Limits

• The tools here do not compress images. Reducing the size of scanned pages requires re-encoding them, which is best done when scanning.
• Signatures are not preserved when merging. A digitally signed PDF is no longer signed once its pages are copied into another file. If the portal requires the original signed file, upload it on its own.
• Form fields and bookmarks are dropped when pages are merged. Fill in and flatten (print to PDF) forms before merging.
• Portal rules change. Always check the current requirements on the portal itself; the typical limits mentioned here are examples, not rules.

Sources and further reading

• ISO 32000-2 (PDF 2.0) — free from the PDF Association
• pdf-lib: the library used to merge, split and reorder pages on this site
• Mozilla pdf.js: the renderer used for thumbnails and image export