BASALT · JOURNAL

What PDF version is my file, and does 1.4 versus 1.7 matter?

2026-10-30 · how to check pdf version

To check a PDF's version on a Mac, open the file in Preview, choose Tools > Show Inspector and read the PDF version line in the General Info pane. In Terminal, head -c 8 document.pdf prints the header, the file's first eight bytes, for example %PDF-1.7. The header isn't always the last word: a /Version entry inside the file can raise it, and Spotlight reports the raised number.

Whether the number matters is a different question. It tells you which features the file is allowed to use, not which ones it uses, and it says nothing about whether the file is safe, clean or well made. A PDF 1.4 file and a PDF 1.7 file can look identical on the screen.

Where the version is written

The version lives in two places. The first is the header, the first line of the file, %PDF-1.4 through %PDF-1.7, or %PDF-2.0 for the newest standard. The second is an optional /Version entry in the document catalog, the root object. When the catalog names a later version than the header, the catalog wins. If it names an earlier one, it's ignored. The entry exists so a program can raise the version of a file by appending a small update, without rewriting the first line.

So a header on its own can understate the file. A tool that reads only the first line reports 1.4 for a file whose catalog says 2.0, and on macOS 15 one of the commands below did exactly that.

What each version added

Each version was a release of the format with new capabilities. The main ones:

• 1.4: transparency, so a page can have see-through objects.
• 1.5: object streams and cross-reference streams, which compress the file's internal structure, and optional content, the layers that can be switched on and off.
• 1.6: AES encryption.
• 1.7: the version that became the international standard ISO 32000-1 in 2008.
• 2.0: ISO 32000-2, published in 2017 and revised in 2020. It deprecates the information dictionary except for the two dates, and it deprecates XFA forms.

None of that is a quality ranking. If a very old or specialized program refuses a file, the version is a reasonable thing to suspect, but a refusal can equally come from encryption, a damaged structure or an unsupported form.

Does 1.4 versus 1.7 matter?

For reading, rarely. For a few jobs, yes.

Archiving and print workflows sometimes name a version in their requirements. PDF/A, the archiving standard, is built on specific versions: PDF/A-1 on PDF 1.4, PDF/A-2 and PDF/A-3 on PDF 1.7, and PDF/A-4 on PDF 2.0 (the PDF Association's ISO 19005 page lists the parts). If a requirement says "PDF 1.4", export with the matching setting in your source application, then check the result with the commands below. Archiving a PDF for the long term goes into that side.

For checking a file's contents, the version matters in one practical way. From 1.5 on, the information dictionary, annotations and other objects can be stored inside compressed object streams. A plain grep on such a file may find nothing even though the data is there. That's why a raw search for an author's name can miss it, and why this post's commands read the structure with qpdf.

A newer version number can also mean more can be hidden. Layers arrived in 1.5, so a file that really follows 1.4 has no optional content groups, which is useful to know when you read what PDF layers can hide. Readers don't police the number, though, so check rather than assume. And a 1.7 file may have no layers at all.

How to check on a Mac

The quick check is Preview's Inspector. Open the file, choose Tools > Show Inspector and look at General Info, which lists File name, Document type, File size, Page size, Page count, Title, Subject, Author, Content creator, PDF Producer, PDF version, Creation date and Modification date. When the exact number matters, use the commands below, which read the header and the effective version separately.

To read the header yourself:

head -c 8 document.pdf

It prints the header, such as %PDF-1.7. A file that doesn't start with %PDF- isn't a standard PDF.

To see the version after any catalog override, ask Spotlight with a test import, which stores nothing in the index:

mdimport -t -d2 document.pdf

Look for kMDItemVersion. On macOS 15 it reported the later of the header and the catalog entry. A test file with a %PDF-1.4 header and /Version /2.0 in its catalog showed kMDItemVersion = "2.0", and one with a 1.7 header and /Version /1.4 showed 1.7. PDFKit, the PDF framework built into macOS, gave the same answers. mdls -name kMDItemVersion document.pdf shows the same field for files that Spotlight has indexed, and prints (null) for files it hasn't.

For the exact structure, install qpdf with brew install qpdf. It only reads here:

qpdf --check document.pdf

The second line says "PDF Version:" followed by the header's number. In the same test file, that line showed 1.4 while the catalog said 2.0, so don't use it alone. To see the catalog entry, find the root object number in the trailer with qpdf --show-object=trailer document.pdf, then print it with --show-object= followed by that number. Look for /Version.

Because the version is only a ceiling, to see what a file actually carries, check its layers, encryption and objects directly. How to see everything a PDF is carrying shows how.

Changing the version

You don't edit the number directly. The version comes from the software that writes the file, so change it by exporting again with a different setting. Some export dialogs offer a compatibility choice, with wording that differs by app. Lowering the version can force the app to flatten transparency or leave out layers, so look at the result. Password protecting a PDF on a Mac also matters here, since AES encryption arrived in 1.6.