PDF basics: what every form-filler should know
Updated 11 October 2026
Almost every Indian recruitment, scholarship and admission portal asks for at least one PDF. Most of the upload errors people hit come from three things: the file is too big, it has the wrong number of pages, or it is password protected. A little background on how PDFs work makes all three easy to fix.
What is a PDF?
PDF stands for Portable Document Format. It was created by Adobe in the early 1990s and is now an open international standard (ISO 32000). The idea is simple: a PDF looks the same on every device. Fonts, layout and page size are fixed, so a certificate opened on a phone in Patna looks the same as on an office computer in Delhi.
A PDF page can contain two very different kinds of content:
- Text and vector graphics, as in a PDF exported from Word or downloaded from DigiLocker. These files are small and the text can be selected and searched.
- Images, as in a scanned document. Each page is effectively a photo. These files are larger and the text cannot be selected unless OCR has been applied.
This is why two "one-page PDFs" can be 40 KB and 2 MB. The guide on compressing scanned PDFs goes deeper into the image kind.
Why forms ask for PDF
- Multiple pages in one file. A three-page certificate stays together.
- Fixed layout. Nothing reflows or changes when an officer opens it.
- Easy to view and print on any system without special software.
- Long-term storage. Organisations archive applications for years.
PDF/A in one paragraph
PDF/A is a version of PDF designed for long-term archiving (ISO 19005). A PDF/A file must embed its fonts, cannot depend on external content, and cannot be encrypted. Most application portals do not require PDF/A, and you do not need to worry about it unless a notice specifically says so. If it does, office software such as Microsoft Word and LibreOffice can export to PDF/A from their Save As or Export options.
Password-protected PDFs and why portals reject them
Some PDFs are encrypted so they open only with a password, and some open freely but are locked by whoever made them against copying or changes. Bank statements, salary slips and e-Aadhaar from UIDAI are common examples.
Upload portals usually reject locked files, or accept them but the officer cannot open them: the portal cannot check the page count, show a preview or read the content without the password.
What to do with a locked PDF
- Look for a version without a password on the issuer's own website or app, or ask the issuer for one.
- If your notice accepts a scan, scan the original document or card, or a printout of it, and make the PDF from the scan with JPG to PDF.
SizeReduce's PDF tools do not open locked PDFs and do not remove passwords or restrictions: a locked file is left as it is.
How to check a PDF's size and page count
| Device | File size | Page count |
|---|---|---|
| Windows PC | Right-click the file, choose Properties, read "Size" | Open in Edge or a PDF reader; the page number box shows "1 of N" |
| Mac | Select the file and press Command + I (Get Info) | Open in Preview; use the sidebar thumbnails or the title bar |
| Android | In your Files app, long-press the file and open its details or info | Open it in a PDF viewer such as Google Drive's viewer |
| iPhone | In the Files app, long-press and choose Get Info | Open it; swipe or use the thumbnail view |
Pay attention to whether the size is in KB or MB, and remember that systems differ on whether 1 KB is 1000 or 1024 bytes. A file Windows shows as 199 KB is about 204,000 bytes, which a strict "200 KB = 200,000 bytes" check could reject. Our KB and MB guide explains this properly.
Worked example: fixing a rejected upload
A notice says: "Upload identity proof in PDF, 1 page, 50 to 300 KB." You upload your e-Aadhaar and get an error.
- Check for a lock. e-Aadhaar is password protected, so the portal may not open it. If the notice accepts a scan, scan your Aadhaar card, or a printout of e-Aadhaar, and make a one-page PDF from it.
- Check pages. The form wants exactly 1 page. If your ID proof is a card with front and back, put both sides on one page instead, for example with PDF to JPG and then JPG to PDF.
- Check size. A text-based PDF can be smaller than a portal's minimum. If yours is, say, 35 KB against a 50 KB minimum, rebuild it as an image PDF at higher quality, which raises the size into the allowed range. Keep the original: the rebuilt copy loses any digital signature the original had.
Good habits
- Keep originals untouched; edit copies.
- Use simple file names without spaces or symbols, like
id-proof.pdf. - Open every file once after creating it. A corrupted or blank PDF is a common reason for rejection at the verification stage.
Questions people ask
- Why does the portal reject my PDF even though it is under the size limit?
- Common reasons are that the PDF is password protected, has more pages than allowed, is corrupted, or is a different file type renamed to .pdf. Check each of these.
- Do I need PDF/A for government job applications?
- Usually not. Only use PDF/A if the notice specifically asks for it.
- How can I see how many pages my PDF has on a phone?
- Open it in any PDF viewer, such as the Google Drive viewer on Android or the Files app on iPhone, and look at the page indicator or thumbnails.
- Can SizeReduce open a password-protected PDF?
- No. Its tools leave locked PDFs as they are. Use a version without a password from the issuer, or, if your notice accepts a scan, scan the document and make the PDF from the scan.