DOC vs DOCX: what's the difference?

DOC: the older format

DOC was Microsoft Word's format until 2003. It's a binary format — compact for its time, but hard for other software to read. You'll mostly see it in older files or from people using very old versions of Word.

DOCX: the modern format

Since Word 2007, DOCX is the standard. It's built on open XML, which makes it smaller, more reliable and easier for other programs (including this website) to work with.

Which one do you have?

Look at the file name: it ends in .doc or .docx. If nothing shows, the document was almost certainly made recently and is a DOCX.

Converting both to PDF

Both formats can become a PDF. Our Word to PDF converter works with DOCX. Have an old .doc file? Open it in Word (or the free Word Online), save it as .docx via File → Save As, and convert it here.