PDF vs DOCX: When to Use Which Format

I get asked this more than you'd think. Someone finishes writing a report or a proposal and goes, "Should I save this as a PDF or just send the Word doc?" And the answer is always the same: it depends on what happens next.

PDF and DOCX aren't competing formats. They do different things. Picking the wrong one doesn't break anything, but it can make your life (or someone else's life) unnecessarily annoying. So let's sort it out.

What Each Format Actually Is

A DOCX file is Microsoft Word's native format. It's been the standard since 2007 when it replaced the older .doc format. It's designed for creating and editing text documents. Think of it as a living document — you open it, change things, save it, pass it along for someone else to change things.

A PDF (Portable Document Format) was invented by Adobe back in the early '90s. The whole point was to create a document that looks exactly the same no matter where you open it. Your computer, my computer, a phone in Tokyo, a printer in your office — same layout, same fonts, same everything.

That core difference drives every decision you'll ever make between the two.

When PDF Is the Right Call

You're sending a final version

If nobody needs to edit this thing, send a PDF. Contracts, invoices, reports you're submitting, applications — anything where the content is locked in. PDFs preserve your formatting perfectly. The margins won't shift because someone has a different version of Word. The fonts won't swap out because they don't have Calibri installed on their Mac.

I learned this the hard way when I sent a Word resume to a recruiter and they opened it on a machine that didn't have my fancy header font. The whole first page looked like a ransom note. Never again.

You need it to look professional

There's a perception thing here too. A PDF feels finished. A Word doc feels like a draft. When you're sending a proposal to a client or submitting something official, PDF signals "this is ready." It's a small thing, but small things add up in professional settings.

You want to control what people can do with it

PDFs let you set permissions. You can make a document read-only, prevent printing, disable copying text, or password protect the whole thing. DOCX files have some protection options too, but they're easier to bypass and less standardized.

You're printing

If something is going to a printer — a flyer, a brochure, a form — PDF is the only real option. It guarantees the output matches what you see on screen. DOCX files can shift layouts between different printers and different versions of Word. I've seen a one-page document turn into a two-page document just because someone printed it from a different computer.

Cross-platform sharing

Not everyone has Microsoft Word. Plenty of people use Google Docs, LibreOffice, Pages, or just their phone's default document viewer. DOCX files can look different in each of those apps. PDFs look the same everywhere because they carry all their formatting information with them. Every modern device can open a PDF natively.

When DOCX Makes More Sense

You're still working on it

This is the obvious one. If the document is a work in progress, keep it in DOCX (or whatever your word processor uses). PDFs are meant to be final. Yes, you can edit PDFs with tools like OnlyDocs, and sometimes you need to — but for active writing and revision, a word processor format is the right tool.

Multiple people are collaborating

If you and three coworkers need to write a report together, DOCX is the way to go. Track changes, comments, suggested edits — Word and Google Docs handle all of that natively. You can technically annotate PDFs and add comments, but it's not the same as true collaborative editing.

The recipient needs to edit it

Sending a template someone needs to fill in? A draft contract the other party's lawyer needs to redline? DOCX. Don't make people jump through hoops to edit something you want them to edit. Sending a locked-down PDF when someone needs to make changes is a passive-aggressive move, intentional or not.

You need complex formatting that might change

If you're working on a document with tables, charts, and embedded images that might need updating, stay in DOCX until it's final. Editing tables in a PDF is doable but painful compared to just doing it in Word.

The "Convert It" Middle Ground

Here's what a lot of people miss: you don't have to choose one format forever. The normal workflow is:

1. Create and edit in DOCX (or Google Docs, or whatever)
2. Convert to PDF when it's done and ready to share

That's it. That's the workflow for 90% of professional documents. Write in Word, export to PDF, send the PDF.

Going the other direction — PDF back to DOCX — is trickier. The conversion is never perfect because PDFs don't store document structure the same way Word does. You'll usually get the text right but the formatting might need cleanup. Still, it works well enough for most situations, and free online converters handle it without installing anything.

Quick Decision Guide

Send as PDF when:

• It's a final version nobody needs to edit
• You're sending it outside your organization
• It's going to be printed
• It contains sensitive info that should be locked down
• You want it to look identical on every device

Send as DOCX when:

• Someone needs to edit it
• You're collaborating with others
• It's an internal draft still in progress
• You're sending a template to be filled out
• The recipient specifically asked for an editable version

When you're unsure: Send both. Attach the PDF as the "official" version and the DOCX as an editable backup. This sounds excessive but it takes ten seconds and saves everyone the "hey can you send me the Word version" email.

What About Google Docs?

Quick sidebar because this comes up a lot. Google Docs uses its own format internally, but it exports to both DOCX and PDF easily. If you're a Google Docs person, the same rules apply — use the Google Doc for editing, export to PDF when you're sharing something final.

One advantage Google Docs has: you can share a link instead of a file. That sidesteps the whole format question because the recipient just opens it in their browser. The downside is they need internet access, and the link can be revoked. For important documents you want someone to keep permanently, sending a file is still better.

File Size Differences

This matters more than people think. A typical DOCX file with just text is pretty small — usually under 100KB. Add some images and it grows, but Word compresses them reasonably well.

PDFs vary wildly. A text-only PDF is tiny. A PDF with high-resolution images or embedded fonts can balloon to tens of megabytes. If file size matters (email attachments, web uploads), you might need to compress your PDF before sending it.

The Bottom Line

PDF is for sharing and preserving. DOCX is for creating and editing. Use DOCX while you're working, convert to PDF when you're done.

Most format headaches come from using the wrong one at the wrong time. A PDF when someone needs to edit. A DOCX when it needs to look perfect on every device. Match the format to the situation and you'll save yourself and everyone else a lot of frustration.

Need to convert between the two? OnlyDocs handles PDF editing, conversion, and more — right in your browser, no software to install, no account required for basic stuff. Worth bookmarking for the next time you're stuck with the wrong format.