How to Check a PDF Version (1.4, 1.7 or 2.0) and What It Means

A PDF's version is a label such as 1.4, 1.7 or 2.0 that the file states about itself. You can read it in under a minute: upload the file to the PDFCheck metadata checker and look at PDF Version, open Document properties in Chrome or Acrobat, or run pdfinfo in a terminal. The harder part is knowing what to do when a portal says the number is wrong.

Three ways to read it

1. PDFCheck. Upload the file on the home page. The report lists PDF Version beside the creator and producer software, page count and encryption status.
2. A viewer. In Chrome's PDF viewer, open the three-dot menu and choose Document properties. In Acrobat Reader, press Ctrl+D (Cmd+D on a Mac) and look under the Description tab.
3. The terminal. With Poppler installed, pdfinfo report.pdf prints a line such as PDF version: 1.7. Nothing leaves your computer. qpdf's --check option also writes information about the file's structure to the terminal, which is useful when a portal complains about more than the version.

The first line of the file holds the same number, for example %PDF-1.4. You can look, but do not edit it. More on that below.

What the numbers mean

Each version added features on top of the previous one. New readers open old files without complaint; old software can fail on new files. The Library of Congress format descriptions for the PDF family and PDF 1.7 are the clearest free summaries I have found.

If Acrobat shows something like "1.7, Adobe Extension Level 3", the file is still PDF 1.7. The extension level marks Acrobat 9 features that came out before PDF 2.0 existed.

Why two tools can show different versions

A PDF can state its version in two places. The header line carries one number. Since PDF 1.4, the document catalog, which is the file's internal table of contents, may carry a later number that overrides the header. The Library of Congress notes that tools reading only the header can misidentify such files.

This happens when software appends changes to an existing file instead of rewriting it. The header still says %PDF-1.4, the catalog says 1.7, and a quick header check reports the lower number.

PDFCheck reads the version with pdfinfo. Only when pdfinfo cannot open the file does it fall back to the %PDF- number in the first kilobyte. The two-file comparer reports the header version. When two tools disagree, the higher number is the one a strict portal will see.

What a rewrite does to the version

I keep a one-page test file whose pdfinfo output reads PDF version: 1.7. Two things happened when I put it through Ghostscript in different ways:

• Run by hand at the /prepress setting, the copy kept version 1.7. Ghostscript's documentation says its default compatibility level is 1.7, and the printer and prepress presets stay there.
• Run through our PDF optimizer, which pins -dCompatibilityLevel=1.4 in every command, the copy came out as PDF 1.4 with the producer changed to GPL Ghostscript 10.08.0 and both dates reset to the moment of conversion.

So the same engine produces different version labels depending on one flag. That is why "which version will I get?" has no answer until you know the exact command or export setting.

Is the version the same as PDF/A?

No. PDF/A is a separate standard for long-term archiving. It limits what a file may contain, for example it requires embedded fonts and bans encryption, and the file declares its conformance in its XMP metadata. A file that says "PDF 1.7" is not PDF/A unless it carries that declaration and follows the rules.

The version only sets a floor. Our PDF/A screen warns when a file declares PDF/A-1 but reports a version below 1.4, or PDF/A-4 below 2.0. That warning is a quick consistency check, not conformance testing.

What to do when a portal rejects the version

1. Read the exact rule. "PDF 1.4 only", "1.7 or earlier" and "PDF/A-2b" need different fixes, and the last one is not about the version at all.
2. Keep the original. Work on a copy with a clear name such as invoice-1042-v14.pdf.
3. Export again from the source. Word, InDesign and most layout tools have a compatibility or PDF version option in their export dialog. This is the cleanest fix because the file is built fresh.
4. Or rewrite the PDF. The optimizer writes PDF 1.4 output as described above. Expect side effects: in our tests the signature was removed, bookmarks and web links were kept, and a fillable text field was dropped. On the command line, qpdf's --min-version raises a version, and --force-version sets an exact one, but its documentation warns that forcing a lower number means qpdf "won't be able to do things like eliminate use of newer image compression schemes". The label changes; the content inside may not match it.
5. Check the new copy. Confirm the version, then open every page, link and form field before you upload.

If the file is digitally signed, stop before step 3. Any rewrite changes the signed bytes. Check with the signature checker first and ask the recipient whether a newly signed copy is acceptable.

Why editing the first line does not work

Changing %PDF-1.7 to %PDF-1.4 in a text editor changes a label and nothing else. The file may still use object streams, JPEG 2000 images or other later features, and the catalog may still declare 1.7. A portal that validates structure will reject it, and a viewer may show a damaged file. Export a new copy instead.

What the version cannot tell you

The version is a promise about which features the file might use, not a certificate that every object follows the rules. It does not show that the file meets PDF/A, PDF/X or PDF/UA, and it cannot guarantee that a specific portal, printer or archive will accept the file. For sharing today, 1.7 is still the safe default; reach for 2.0 when a recipient or a standard such as PDF/A-4 asks for it.

To see the version, producer, dates and encryption status of your own file in one report, check it on PDFCheck.