PDF vs Word: which format should you use?

What each format is designed for

A Word document (.docx) is designed to be edited. Its content flows: change a font or add a paragraph and everything below rearranges itself. A PDF is designed to be read and shared. Every element is placed at a fixed position, so the page looks the same on any device, printer or operating system.

When to use Word

• While you are writing, reviewing or collaborating, especially with tracked changes and comments.
• When the document is a template that others will fill in and change.
• When you expect frequent updates to the text.

When to use PDF

• When you send a final version, such as a CV, invoice, contract or report.
• When the layout must not change, for example for printing.
• When you do not want the reader to edit the content casually.
• When you combine several documents into one file, which is what PDF is good at.

Converting from Word to PDF

This is the easy direction. Write and finalise the document in Word, then convert it to PDF for sharing. Check the result before you send it, because complex layouts can shift slightly in conversion.

Converting from PDF to Word

This direction is harder, because a PDF does not store paragraphs, tables and styles the way Word does. It stores positioned text. A converter can extract the text into an editable document, but the original layout, columns and images usually need rebuilding by hand. Scanned PDFs contain no text at all and need OCR first.

For that reason, always keep the original Word file. If you only have the PDF, use PDF to Word to recover the text, then reapply formatting.

A simple rule

Edit in Word, share in PDF. Keep both versions, and name them clearly so you always know which one is the editable source.

How the two formats handle layout

The essential difference is flow. In a Word file, text flows: add a sentence and everything after it moves down, page breaks shift, and tables reflow. In a PDF, nothing flows. Every character sits at a fixed position, so nothing moves when you open the file on a different computer, a phone or a printer.

That is why the PDF is the safe choice for anything where appearance must be exact, and the Word file is the right choice while the content is still changing.

Editing, collaboration and version control

Word offers tracked changes and comments, which are designed for reviewing a document with others. PDF readers offer annotation tools such as highlights and notes, which are good for marking up a finished document but not for rewriting it.

A sensible workflow is to draft and review in Word, then produce the PDF only when the text is agreed. If someone finds a mistake afterwards, correct the Word file and create a fresh PDF, rather than trying to edit the PDF directly. That keeps one editable source of truth.

Security and file size

A PDF is harder to change accidentally, which makes it suitable for documents that should stay as issued, such as invoices and signed agreements. It is not a security measure on its own, though. Skilled people can edit PDFs with the right software.

File size depends on content rather than format. A text-only document is small in either format. Documents with many photographs are large in both. If you need to send something big, reduce image size at the source before creating the file.

Accessibility and reading experience

Word documents that use proper heading and list styles can be read well by screen readers, and readers can adjust the text size easily. A PDF made from such a document can keep that structure, but a PDF made from a scan is just a picture and cannot be read by a screen reader at all. On small screens, a fixed-layout PDF can require zooming and scrolling, whereas flowing text adapts to the screen.

If your audience will mostly read on phones, consider whether a web page or a reflowable format would serve them better than a fixed A4 page.

Quick decision guide

• Still writing or reviewing: use Word.
• Sending a final version to be read or printed: use PDF.
• Need the recipient to fill in or edit content: send Word, or a form built for the purpose.
• Combining multiple documents into one pack: use PDF and merge them.
• Need to recover text from a PDF: convert to Word or extract the text, then check and tidy it.

Common mistakes with each format

Most problems come down to one habit: keep the editable file, produce the PDF last, and open the PDF once before sending it. These are the mistakes that happen without it.

• Sending a Word file as a final document and having it look different on the recipient's computer.
• Overwriting the only editable copy after saving a PDF, and later discovering you cannot easily change the text.
• Trying to edit a PDF directly for a large rewrite, when it would be faster to start again from the source document.
• Sending a scanned PDF and assuming the recipient can search or copy the text.
• Forgetting to check a converted document before sending, which is where most layout problems get caught.