Does the version affect what I can do?

Rarely. Very old versions lack transparency and modern compression.

Not directly. Rebuilding the document through most tools produces a current version.

Which version should I want?

Anything from 1.4 onwards is readable everywhere in current use.

inspect

What PDF Version Is My File

See which version of the PDF format a file uses.

Runs in your browser

How it works

Reads the version declared in the file header. It matters rarely but decisively: an old version may lack transparency and modern compression, and some archival and print workflows require a specific one.

Related tools

Inspect PDF

/inspect-pdf

PDF Permissions Inspector

/pdf-permissions-inspector

View PDF Metadata

/view-pdf-metadata

Questions

Does the version affect what I can do?: Rarely. Very old versions lack transparency and modern compression.
Can I change it?: Not directly. Rebuilding the document through most tools produces a current version.
Which version should I want?: Anything from 1.4 onwards is readable everywhere in current use.